lnd/lnwallet/channel_test.go

package lnwallet

import (
	"bytes"
	"context"
	crand "crypto/rand"
	"crypto/sha256"
	"errors"
	"fmt"
	"math/rand"
	"reflect"
	"runtime"
	"testing"
	"testing/quick"
	"time"

	"github.com/btcsuite/btcd/blockchain"
	"github.com/btcsuite/btcd/btcec/v2"
	"github.com/btcsuite/btcd/btcec/v2/schnorr/musig2"
	"github.com/btcsuite/btcd/btcutil"
	"github.com/btcsuite/btcd/btcutil/txsort"
	"github.com/btcsuite/btcd/chaincfg/chainhash"
	"github.com/btcsuite/btcd/txscript"
	"github.com/btcsuite/btcd/wire"
	"github.com/davecgh/go-spew/spew"
	"github.com/lightningnetwork/lnd/chainntnfs"
	"github.com/lightningnetwork/lnd/channeldb"
	"github.com/lightningnetwork/lnd/channeldb/models"
	"github.com/lightningnetwork/lnd/fn"
	"github.com/lightningnetwork/lnd/input"
	"github.com/lightningnetwork/lnd/lntypes"
	"github.com/lightningnetwork/lnd/lnwallet/chainfee"
	"github.com/lightningnetwork/lnd/lnwire"
	"github.com/lightningnetwork/lnd/tlv"
	"github.com/stretchr/testify/mock"
	"github.com/stretchr/testify/require"
)

// createHTLC is a utility function for generating an HTLC with a given
// preimage and a given amount.
func createHTLC(id int, amount lnwire.MilliSatoshi) (*lnwire.UpdateAddHTLC, [32]byte) {
	preimage := bytes.Repeat([]byte{byte(id)}, 32)
	paymentHash := sha256.Sum256(preimage)

	var returnPreimage [32]byte
	copy(returnPreimage[:], preimage)

	return &lnwire.UpdateAddHTLC{
		ID:          uint64(id),
		PaymentHash: paymentHash,
		Amount:      amount,
		Expiry:      uint32(5),
	}, returnPreimage
}

// addAndReceiveHTLC adds an HTLC as local to the first channel, and as remote
// to a second channel. The HTLC ID is not modified.
func addAndReceiveHTLC(t *testing.T, channel1, channel2 *LightningChannel,
	htlc *lnwire.UpdateAddHTLC, openKey *models.CircuitKey) {

	_, err := channel1.AddHTLC(htlc, openKey)
	require.NoErrorf(t, err, "channel 1 unable to add htlc: %v", err)

	_, err = channel2.ReceiveHTLC(htlc)
	require.NoErrorf(t, err, "channel 2 unable to recv htlc: %v", err)
}

func assertOutputExistsByValue(t *testing.T, commitTx *wire.MsgTx,
	value btcutil.Amount) {

	for _, txOut := range commitTx.TxOut {
		if txOut.Value == int64(value) {
			return
		}
	}

	t.Fatalf("unable to find output of value %v within tx %v", value,
		spew.Sdump(commitTx))
}

// testAddSettleWorkflow tests a simple channel scenario where Alice and Bob
// add, the settle an HTLC between themselves.
func testAddSettleWorkflow(t *testing.T, tweakless bool,
	chanTypeModifier channeldb.ChannelType,
	storeFinalHtlcResolutions bool) {

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	chanType := channeldb.SingleFunderTweaklessBit
	if !tweakless {
		chanType = channeldb.SingleFunderBit
	}

	if chanTypeModifier != 0 {
		chanType |= chanTypeModifier
	}

	aliceChannel, bobChannel, err := CreateTestChannels(
		t, chanType,
		channeldb.OptionStoreFinalHtlcResolutions(
			storeFinalHtlcResolutions,
		),
	)
	require.NoError(t, err, "unable to create test channels")

	paymentPreimage := bytes.Repeat([]byte{1}, 32)
	paymentHash := sha256.Sum256(paymentPreimage)
	htlcAmt := lnwire.NewMSatFromSatoshis(btcutil.SatoshiPerBitcoin)
	htlc := &lnwire.UpdateAddHTLC{
		PaymentHash: paymentHash,
		Amount:      htlcAmt,
		Expiry:      uint32(5),
	}

	// First Alice adds the outgoing HTLC to her local channel's state
	// update log. Then Alice sends this wire message over to Bob who adds
	// this htlc to his remote state update log.
	aliceHtlcIndex, err := aliceChannel.AddHTLC(htlc, nil)
	require.NoError(t, err, "unable to add htlc")

	bobHtlcIndex, err := bobChannel.ReceiveHTLC(htlc)
	require.NoError(t, err, "unable to recv htlc")

	// Next alice commits this change by sending a signature message. Since
	// we expect the messages to be ordered, Bob will receive the HTLC we
	// just sent before he receives this signature, so the signature will
	// cover the HTLC.
	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "alice unable to sign commitment")

	// Bob receives this signature message, and checks that this covers the
	// state he has in his remote log. This includes the HTLC just sent
	// from Alice.
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err, "bob unable to process alice's new commitment")

	// Bob revokes his prior commitment given to him by Alice, since he now
	// has a valid signature for a newer commitment.
	bobRevocation, _, _, err := bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to generate bob revocation")

	// Bob finally send a signature for Alice's commitment transaction.
	// This signature will cover the HTLC, since Bob will first send the
	// revocation just created. The revocation also acks every received
	// HTLC up to the point where Alice sent here signature.
	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "bob unable to sign alice's commitment")

	// Alice then processes this revocation, sending her own revocation for
	// her prior commitment transaction. Alice shouldn't have any HTLCs to
	// forward since she's sending an outgoing HTLC.
	fwdPkg, _, err := aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err, "alice unable to process bob's revocation")
	if len(fwdPkg.Adds) != 0 {
		t.Fatalf("alice forwards %v add htlcs, should forward none",
			len(fwdPkg.Adds))
	}
	if len(fwdPkg.SettleFails) != 0 {
		t.Fatalf("alice forwards %v settle/fail htlcs, "+
			"should forward none", len(fwdPkg.SettleFails))
	}

	// Alice then processes bob's signature, and since she just received
	// the revocation, she expect this signature to cover everything up to
	// the point where she sent her signature, including the HTLC.
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err, "alice unable to process bob's new commitment")

	// Alice then generates a revocation for bob.
	aliceRevocation, _, _, err := aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to revoke alice channel")

	// Finally Bob processes Alice's revocation, at this point the new HTLC
	// is fully locked in within both commitment transactions. Bob should
	// also be able to forward an HTLC now that the HTLC has been locked
	// into both commitment transactions.
	fwdPkg, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err, "bob unable to process alice's revocation")
	if len(fwdPkg.Adds) != 1 {
		t.Fatalf("bob forwards %v add htlcs, should only forward one",
			len(fwdPkg.Adds))
	}
	if len(fwdPkg.SettleFails) != 0 {
		t.Fatalf("bob forwards %v settle/fail htlcs, "+
			"should forward none", len(fwdPkg.SettleFails))
	}

	// At this point, both sides should have the proper number of satoshis
	// sent, and commitment height updated within their local channel
	// state.
	aliceSent := lnwire.MilliSatoshi(0)
	bobSent := lnwire.MilliSatoshi(0)

	if aliceChannel.channelState.TotalMSatSent != aliceSent {
		t.Fatalf("alice has incorrect milli-satoshis sent: %v vs %v",
			aliceChannel.channelState.TotalMSatSent, aliceSent)
	}
	if aliceChannel.channelState.TotalMSatReceived != bobSent {
		t.Fatalf("alice has incorrect milli-satoshis received %v vs %v",
			aliceChannel.channelState.TotalMSatReceived, bobSent)
	}
	if bobChannel.channelState.TotalMSatSent != bobSent {
		t.Fatalf("bob has incorrect milli-satoshis sent %v vs %v",
			bobChannel.channelState.TotalMSatSent, bobSent)
	}
	if bobChannel.channelState.TotalMSatReceived != aliceSent {
		t.Fatalf("bob has incorrect milli-satoshis received %v vs %v",
			bobChannel.channelState.TotalMSatReceived, aliceSent)
	}
	if bobChannel.currentHeight != 1 {
		t.Fatalf("bob has incorrect commitment height, %v vs %v",
			bobChannel.currentHeight, 1)
	}
	if aliceChannel.currentHeight != 1 {
		t.Fatalf("alice has incorrect commitment height, %v vs %v",
			aliceChannel.currentHeight, 1)
	}

	aliceChanState := aliceChannel.channelState
	bobChanState := bobChannel.channelState

	// Both commitment transactions should have three outputs, and one of
	// them should be exactly the amount of the HTLC.
	numOutputs := 3
	if chanTypeModifier.HasAnchors() {
		// In this case we expect two extra outputs as both sides need
		// an anchor output.
		numOutputs = 5
	}
	if len(aliceChanState.LocalCommitment.CommitTx.TxOut) != numOutputs {
		t.Fatalf("alice should have three commitment outputs, instead "+
			"have %v",
			len(aliceChanState.LocalCommitment.CommitTx.TxOut))
	}
	if len(bobChanState.LocalCommitment.CommitTx.TxOut) != numOutputs {
		t.Fatalf("bob should have three commitment outputs, instead "+
			"have %v",
			len(bobChanState.LocalCommitment.CommitTx.TxOut))
	}
	assertOutputExistsByValue(t,
		aliceChannel.channelState.LocalCommitment.CommitTx,
		htlcAmt.ToSatoshis())
	assertOutputExistsByValue(t,
		bobChannel.channelState.LocalCommitment.CommitTx,
		htlcAmt.ToSatoshis())

	// Now we'll repeat a similar exchange, this time with Bob settling the
	// HTLC once he learns of the preimage.
	var preimage [32]byte
	copy(preimage[:], paymentPreimage)
	err = bobChannel.SettleHTLC(preimage, bobHtlcIndex, nil, nil, nil)
	require.NoError(t, err, "bob unable to settle inbound htlc")

	err = aliceChannel.ReceiveHTLCSettle(preimage, aliceHtlcIndex)
	if err != nil {
		t.Fatalf("alice unable to accept settle of outbound htlc: %v", err)
	}

	bobNewCommit, err = bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "bob unable to sign settle commitment")
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err, "alice unable to process bob's new commitment")

	aliceRevocation2, _, _, err := aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "alice unable to generate revocation")
	aliceNewCommit, err = aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "alice unable to sign new commitment")

	fwdPkg, _, err = bobChannel.ReceiveRevocation(aliceRevocation2)
	require.NoError(t, err, "bob unable to process alice's revocation")
	if len(fwdPkg.Adds) != 0 {
		t.Fatalf("bob forwards %v add htlcs, should forward none",
			len(fwdPkg.Adds))
	}
	if len(fwdPkg.SettleFails) != 0 {
		t.Fatalf("bob forwards %v settle/fail htlcs, "+
			"should forward none", len(fwdPkg.SettleFails))
	}

	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err, "bob unable to process alice's new commitment")

	bobRevocation2, _, finalHtlcs, err := bobChannel.
		RevokeCurrentCommitment()
	require.NoError(t, err, "bob unable to revoke commitment")

	// Check finalHtlcs for the expected final resolution.
	require.Len(t, finalHtlcs, 1, "final htlc expected")
	for htlcID, settled := range finalHtlcs {
		require.True(t, settled, "final settle expected")

		// Assert that final resolution was stored in Bob's database if
		// storage is enabled.
		finalInfo, err := bobChannel.channelState.Db.LookupFinalHtlc(
			bobChannel.ShortChanID(), htlcID,
		)
		if storeFinalHtlcResolutions {
			require.NoError(t, err)
			require.True(t, finalInfo.Offchain)
			require.True(t, finalInfo.Settled)
		} else {
			require.ErrorIs(t, err, channeldb.ErrHtlcUnknown)
		}
	}

	fwdPkg, _, err = aliceChannel.ReceiveRevocation(bobRevocation2)
	require.NoError(t, err, "alice unable to process bob's revocation")
	if len(fwdPkg.Adds) != 0 {
		// Alice should now be able to forward the settlement HTLC to
		// any down stream peers.
		t.Fatalf("alice should be forwarding an add HTLC, "+
			"instead forwarding %v: %v", len(fwdPkg.Adds),
			spew.Sdump(fwdPkg.Adds))
	}
	if len(fwdPkg.SettleFails) != 1 {
		t.Fatalf("alice should be forwarding one settle/fails HTLC, "+
			"instead forwarding: %v", len(fwdPkg.SettleFails))
	}

	// At this point, Bob should have 6 BTC settled, with Alice still
	// having 4 BTC. Alice's channel should show 1 BTC sent and Bob's
	// channel should show 1 BTC received. They should also be at
	// commitment height two, with the revocation window extended by 1 (5).
	mSatTransferred := lnwire.NewMSatFromSatoshis(btcutil.SatoshiPerBitcoin)
	if aliceChannel.channelState.TotalMSatSent != mSatTransferred {
		t.Fatalf("alice satoshis sent incorrect %v vs %v expected",
			aliceChannel.channelState.TotalMSatSent,
			mSatTransferred)
	}
	if aliceChannel.channelState.TotalMSatReceived != 0 {
		t.Fatalf("alice satoshis received incorrect %v vs %v expected",
			aliceChannel.channelState.TotalMSatReceived, 0)
	}
	if bobChannel.channelState.TotalMSatReceived != mSatTransferred {
		t.Fatalf("bob satoshis received incorrect %v vs %v expected",
			bobChannel.channelState.TotalMSatReceived,
			mSatTransferred)
	}
	if bobChannel.channelState.TotalMSatSent != 0 {
		t.Fatalf("bob satoshis sent incorrect %v vs %v expected",
			bobChannel.channelState.TotalMSatSent, 0)
	}
	if bobChannel.currentHeight != 2 {
		t.Fatalf("bob has incorrect commitment height, %v vs %v",
			bobChannel.currentHeight, 2)
	}
	if aliceChannel.currentHeight != 2 {
		t.Fatalf("alice has incorrect commitment height, %v vs %v",
			aliceChannel.currentHeight, 2)
	}

	// The logs of both sides should now be cleared since the entry adding
	// the HTLC should have been removed once both sides receive the
	// revocation.
	if aliceChannel.updateLogs.Local.Len() != 0 {
		t.Fatalf("alice's local not updated, should be empty, has %v "+
			"entries instead", aliceChannel.updateLogs.Local.Len())
	}
	if aliceChannel.updateLogs.Remote.Len() != 0 {
		t.Fatalf("alice's remote not updated, should be empty, has %v "+
			"entries instead", aliceChannel.updateLogs.Remote.Len())
	}
	if len(aliceChannel.updateLogs.Local.updateIndex) != 0 {
		t.Fatalf("alice's local log index not cleared, should be "+
			"empty but has %v entries",
			len(aliceChannel.updateLogs.Local.updateIndex))
	}
	if len(aliceChannel.updateLogs.Remote.updateIndex) != 0 {
		t.Fatalf("alice's remote log index not cleared, should be "+
			"empty but has %v entries",
			len(aliceChannel.updateLogs.Remote.updateIndex))
	}
}

// TestSimpleAddSettleWorkflow tests a simple channel scenario wherein the
// local node (Alice in this case) creates a new outgoing HTLC to bob, commits
// this change, then bob immediately commits a settlement of the HTLC after the
// initial add is fully committed in both commit chains.
//
// TODO(roasbeef): write higher level framework to exercise various states of
// the state machine
//   - DSL language perhaps?
//   - constructed via input/output files
func TestSimpleAddSettleWorkflow(t *testing.T) {
	t.Parallel()

	for _, tweakless := range []bool{true, false} {
		tweakless := tweakless

		t.Run(fmt.Sprintf("tweakless=%v", tweakless), func(t *testing.T) {
			testAddSettleWorkflow(t, tweakless, 0, false)
		})
	}

	t.Run("anchors", func(t *testing.T) {
		testAddSettleWorkflow(
			t, true,
			channeldb.AnchorOutputsBit|channeldb.ZeroHtlcTxFeeBit,
			false,
		)
	})

	t.Run("taproot", func(t *testing.T) {
		testAddSettleWorkflow(
			t, true, channeldb.SimpleTaprootFeatureBit, false,
		)
	})

	t.Run("taproot with tapscript root", func(t *testing.T) {
		flags := channeldb.SimpleTaprootFeatureBit |
			channeldb.TapscriptRootBit
		testAddSettleWorkflow(t, true, flags, false)
	})

	t.Run("storeFinalHtlcResolutions=true", func(t *testing.T) {
		testAddSettleWorkflow(t, false, 0, true)
	})
}

// TestChannelZeroAddLocalHeight tests that we properly set the addCommitHeightLocal
// field during state log restoration.
//
// The full state transition of this test is:
//
// Alice                   Bob
//
//	-----add------>
//	-----sig------>
//	<----rev-------
//	<----sig-------
//	-----rev------>
//	<---settle-----
//	<----sig-------
//	-----rev------>
//	  *alice dies*
//	<----add-------
//	x----sig-------
//
// The last sig will be rejected if addCommitHeightLocal is not set for the
// initial add that Alice sent. This test checks that this behavior does
// not occur and that we properly set the addCommitHeightLocal field.
func TestChannelZeroAddLocalHeight(t *testing.T) {
	t.Parallel()

	// Create a test channel so that we can test the buggy behavior.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err)

	// First we create an HTLC that Alice sends to Bob.
	htlc, _ := createHTLC(0, lnwire.MilliSatoshi(500000))

	// -----add----->
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)

	// Force a state transition to lock in this add on both commitments.
	// -----sig----->
	// <----rev------
	// <----sig------
	// -----rev----->
	err = ForceStateTransition(aliceChannel, bobChannel)
	require.NoError(t, err)

	// Now Bob should fail the htlc back to Alice.
	// <----fail-----
	err = bobChannel.FailHTLC(0, []byte("failreason"), nil, nil, nil)
	require.NoError(t, err)
	err = aliceChannel.ReceiveFailHTLC(0, []byte("bad"))
	require.NoError(t, err)

	// Bob should send a commitment signature to Alice.
	// <----sig------
	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err)

	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err)

	// Alice should reply with a revocation.
	// -----rev----->
	aliceRevocation, _, _, err := aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err)

	_, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err)

	// We now restore Alice's channel as this was the point at which
	// the addCommitHeightLocal field wouldn't be set, causing a force
	// close.
	newAliceChannel, err := NewLightningChannel(
		aliceChannel.Signer, aliceChannel.channelState,
		aliceChannel.sigPool,
	)
	require.NoError(t, err)

	// Bob now sends an htlc to Alice
	htlc2, _ := createHTLC(0, lnwire.MilliSatoshi(500000))

	// <----add-----
	addAndReceiveHTLC(t, bobChannel, newAliceChannel, htlc2, nil)

	// Bob should now send a commitment signature to Alice.
	// <----sig-----
	bobNewCommit, err = bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err)

	// Alice should accept the commitment. Previously she would
	// force close here.
	err = newAliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err)
}

// TestCheckCommitTxSize checks that estimation size of commitment
// transaction with some degree of error corresponds to the actual size.
func TestCheckCommitTxSize(t *testing.T) {
	t.Parallel()

	checkSize := func(channel *LightningChannel, count int) {
		// Due to variable size of the signatures (70-73) in
		// witness script actual size of commitment transaction might
		// be lower on 6 weight.
		BaseCommitmentTxSizeEstimationError := 6

		commitTx, err := channel.getSignedCommitTx()
		if err != nil {
			t.Fatalf("unable to initiate alice force close: %v", err)
		}

		actualCost := blockchain.GetTransactionWeight(btcutil.NewTx(commitTx))
		estimatedCost := input.EstimateCommitTxWeight(count, false)

		diff := int(estimatedCost - actualCost)
		if 0 > diff || BaseCommitmentTxSizeEstimationError < diff {
			t.Fatalf("estimation is wrong, diff: %v", diff)
		}

	}

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// Check that weight estimation of the commitment transaction without
	// HTLCs is right.
	checkSize(aliceChannel, 0)
	checkSize(bobChannel, 0)

	// Adding HTLCs and check that size stays in allowable estimation
	// error window.
	for i := 0; i <= 10; i++ {
		htlc, _ := createHTLC(i, lnwire.MilliSatoshi(1e7))

		addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)

		if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
			t.Fatalf("unable to complete state update: %v", err)
		}
		checkSize(aliceChannel, i+1)
		checkSize(bobChannel, i+1)
	}

	// Settle HTLCs and check that estimation is counting cost of settle
	// HTLCs properly.
	for i := 10; i >= 0; i-- {
		_, preimage := createHTLC(i, lnwire.MilliSatoshi(1e7))

		err := bobChannel.SettleHTLC(preimage, uint64(i), nil, nil, nil)
		if err != nil {
			t.Fatalf("bob unable to settle inbound htlc: %v", err)
		}

		err = aliceChannel.ReceiveHTLCSettle(preimage, uint64(i))
		if err != nil {
			t.Fatalf("alice unable to accept settle of outbound htlc: %v", err)
		}

		if err := ForceStateTransition(bobChannel, aliceChannel); err != nil {
			t.Fatalf("unable to complete state update: %v", err)
		}
		checkSize(aliceChannel, i)
		checkSize(bobChannel, i)
	}
}

// TestCommitHTLCSigTieBreak asserts that HTLC signatures are sent the proper
// BIP69+CLTV sorting expected by BOLT 3 when multiple HTLCs have identical
// payment hashes and amounts, but differing CLTVs. This is exercised by adding
// the HTLCs in the descending order of their CLTVs, and asserting that their
// order is reversed when signing.
func TestCommitHTLCSigTieBreak(t *testing.T) {
	t.Run("no restart", func(t *testing.T) {
		testCommitHTLCSigTieBreak(t, false)
	})
	t.Run("restart", func(t *testing.T) {
		testCommitHTLCSigTieBreak(t, true)
	})
}

func testCommitHTLCSigTieBreak(t *testing.T, restart bool) {
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	if err != nil {
		t.Fatalf("unable to create test channels; %v", err)
	}

	const (
		htlcAmt  = lnwire.MilliSatoshi(20000000)
		numHtlcs = 2
	)

	// Add HTLCs with identical payment hashes and amounts, but descending
	// CLTV values. We will expect the signatures to appear in the reverse
	// order that the HTLCs are added due to the commitment sorting.
	for i := 0; i < numHtlcs; i++ {
		var (
			preimage lntypes.Preimage
			hash     = preimage.Hash()
		)

		htlc := &lnwire.UpdateAddHTLC{
			ID:          uint64(i),
			PaymentHash: hash,
			Amount:      htlcAmt,
			Expiry:      uint32(numHtlcs - i),
		}

		addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)
	}

	// Have Alice initiate the first half of the commitment dance. The
	// tie-breaking for commitment sorting won't affect the commitment
	// signed by Alice because received HTLC scripts commit to the CLTV
	// directly, so the outputs will have different scriptPubkeys.
	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign alice's commitment")

	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err, "unable to receive alice's commitment")

	bobRevocation, _, _, err := bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to revoke bob's commitment")
	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err, "unable to receive bob's revocation")

	// Now have Bob initiate the second half of the commitment dance. Here
	// the offered HTLC scripts he adds for Alice will need to have the
	// tie-breaking applied because the CLTV is not committed, but instead
	// implicit via the construction of the second-level transactions.
	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign bob's commitment")

	if len(bobNewCommit.PendingHTLCs) != numHtlcs {
		t.Fatalf("expected %d htlcs, got: %v", numHtlcs,
			len(bobNewCommit.PendingHTLCs))
	}

	// Ensure that our HTLCs appear in the reverse order from which they
	// were added by inspecting each's outpoint index. We expect the output
	// indexes to be in descending order, i.e. the first HTLC added had the
	// highest CLTV and should end up last.
	lastIndex := bobNewCommit.PendingHTLCs[0].OutputIndex
	for i, htlc := range bobNewCommit.PendingHTLCs[1:] {
		if htlc.OutputIndex >= lastIndex {
			t.Fatalf("htlc %d output index %d is not descending",
				i, htlc.OutputIndex)
		}

		lastIndex = htlc.OutputIndex
	}

	// If requested, restart Alice so that we can test that the necessary
	// indexes can be reconstructed before needing to validate the
	// signatures from Bob.
	if restart {
		aliceState := aliceChannel.channelState
		aliceChannels, err := aliceState.Db.FetchOpenChannels(
			aliceState.IdentityPub,
		)
		if err != nil {
			t.Fatalf("unable to fetch channel: %v", err)
		}

		aliceChannelNew, err := NewLightningChannel(
			aliceChannel.Signer, aliceChannels[0],
			aliceChannel.sigPool,
		)
		if err != nil {
			t.Fatalf("unable to create new channel: %v", err)
		}

		aliceChannel = aliceChannelNew
	}

	// Finally, have Alice validate the signatures to ensure that she is
	// expecting the signatures in the proper order.
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err, "unable to receive bob's commitment")
}

// TestCommitHTLCSigCustomRecordSize asserts that custom records produced for
// a commitment_signed message are properly limited in size.
func TestCommitHTLCSigCustomRecordSize(t *testing.T) {
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SimpleTaprootFeatureBit|
			channeldb.TapscriptRootBit,
	)
	require.NoError(t, err, "unable to create test channels")

	const (
		htlcAmt  = lnwire.MilliSatoshi(20000000)
		numHtlcs = 2
	)

	largeRecords := lnwire.CustomRecords{
		lnwire.MinCustomRecordsTlvType: bytes.Repeat([]byte{0}, 65_500),
	}
	largeBlob, err := largeRecords.Serialize()
	require.NoError(t, err)

	aliceChannel.auxSigner.WhenSome(func(a AuxSigner) {
		mockSigner, ok := a.(*MockAuxSigner)
		require.True(t, ok, "expected MockAuxSigner")

		// Replace the default PackSigs implementation to return a
		// large custom records blob.
		mockSigner.ExpectedCalls = fn.Filter(func(c *mock.Call) bool {
			return c.Method != "PackSigs"
		}, mockSigner.ExpectedCalls)
		mockSigner.On("PackSigs", mock.Anything).
			Return(fn.Ok(fn.Some(largeBlob)))
	})

	// Add HTLCs with identical payment hashes and amounts, but descending
	// CLTV values. We will expect the signatures to appear in the reverse
	// order that the HTLCs are added due to the commitment sorting.
	for i := 0; i < numHtlcs; i++ {
		var (
			preimage lntypes.Preimage
			hash     = preimage.Hash()
		)

		htlc := &lnwire.UpdateAddHTLC{
			ID:          uint64(i),
			PaymentHash: hash,
			Amount:      htlcAmt,
			Expiry:      uint32(numHtlcs - i),
		}

		if _, err := aliceChannel.AddHTLC(htlc, nil); err != nil {
			t.Fatalf("alice unable to add htlc: %v", err)
		}
		if _, err := bobChannel.ReceiveHTLC(htlc); err != nil {
			t.Fatalf("bob unable to receive htlc: %v", err)
		}
	}

	// We expect an error because of the large custom records blob.
	_, err = aliceChannel.SignNextCommitment(ctxb)
	require.ErrorContains(t, err, "exceeds max allowed size")
}

// TestCooperativeChannelClosure checks that the coop close process finishes
// with an agreement from both parties, and that the final balances of the
// close tx check out.
func TestCooperativeChannelClosure(t *testing.T) {
	t.Run("tweakless", func(t *testing.T) {
		testCoopClose(t, &coopCloseTestCase{
			chanType: channeldb.SingleFunderTweaklessBit,
		})
	})
	t.Run("anchors", func(t *testing.T) {
		testCoopClose(t, &coopCloseTestCase{
			chanType: channeldb.SingleFunderTweaklessBit |
				channeldb.AnchorOutputsBit,
			anchorAmt: AnchorSize * 2,
		})
	})
}

type coopCloseTestCase struct {
	chanType  channeldb.ChannelType
	anchorAmt btcutil.Amount
}

func testCoopClose(t *testing.T, testCase *coopCloseTestCase) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, testCase.chanType,
	)
	require.NoError(t, err, "unable to create test channels")

	aliceDeliveryScript := bobsPrivKey[:]
	bobDeliveryScript := testHdSeed[:]

	aliceFeeRate := chainfee.SatPerKWeight(
		aliceChannel.channelState.LocalCommitment.FeePerKw,
	)
	bobFeeRate := chainfee.SatPerKWeight(
		bobChannel.channelState.LocalCommitment.FeePerKw,
	)

	// We'll start with both Alice and Bob creating a new close proposal
	// with the same fee.
	aliceFee := aliceChannel.CalcFee(aliceFeeRate)
	aliceSig, _, _, err := aliceChannel.CreateCloseProposal(
		aliceFee, aliceDeliveryScript, bobDeliveryScript,
	)
	require.NoError(t, err, "unable to create alice coop close proposal")

	bobFee := bobChannel.CalcFee(bobFeeRate)
	bobSig, _, _, err := bobChannel.CreateCloseProposal(
		bobFee, bobDeliveryScript, aliceDeliveryScript,
	)
	require.NoError(t, err, "unable to create bob coop close proposal")

	// With the proposals created, both sides should be able to properly
	// process the other party's signature. This indicates that the
	// transaction is well formed, and the signatures verify.
	aliceCloseTx, bobTxBalance, err := bobChannel.CompleteCooperativeClose(
		bobSig, aliceSig, bobDeliveryScript, aliceDeliveryScript,
		bobFee,
	)
	require.NoError(t, err, "unable to complete alice cooperative close")
	bobCloseSha := aliceCloseTx.TxHash()

	bobCloseTx, aliceTxBalance, err := aliceChannel.CompleteCooperativeClose(
		aliceSig, bobSig, aliceDeliveryScript, bobDeliveryScript,
		aliceFee,
	)
	require.NoError(t, err, "unable to complete bob cooperative close")
	aliceCloseSha := bobCloseTx.TxHash()

	if bobCloseSha != aliceCloseSha {
		t.Fatalf("alice and bob close transactions don't match: %v", err)
	}

	// Finally, make sure the final balances are correct from both's
	// perspective.
	aliceBalance := aliceChannel.channelState.LocalCommitment.
		LocalBalance.ToSatoshis()

	// The commit balance have had the initiator's (Alice) commitfee and
	// any anchors subtracted, so add that back to the final expected
	// balance. Alice also pays the coop close fee, so that must be
	// subtracted.
	commitFee := aliceChannel.channelState.LocalCommitment.CommitFee
	expBalanceAlice := aliceBalance + commitFee +
		testCase.anchorAmt - bobFee
	if aliceTxBalance != expBalanceAlice {
		t.Fatalf("expected balance %v got %v", expBalanceAlice,
			aliceTxBalance)
	}

	// Bob is not the initiator, so his final balance should simply be
	// equal to the latest commitment balance.
	expBalanceBob := bobChannel.channelState.LocalCommitment.
		LocalBalance.ToSatoshis()
	if bobTxBalance != expBalanceBob {
		t.Fatalf("expected bob's balance to be %v got %v",
			expBalanceBob, bobTxBalance)
	}
}

// TestForceClose checks that the resulting ForceCloseSummary is correct when a
// peer is ForceClosing the channel. Will check outputs both above and below
// the dust limit. Additionally, we'll ensure that the node which executed the
// force close generates HTLC resolutions that are capable of sweeping both
// incoming and outgoing HTLC's.
func TestForceClose(t *testing.T) {
	t.Run("tweakless", func(t *testing.T) {
		testForceClose(t, &forceCloseTestCase{
			chanType:             channeldb.SingleFunderTweaklessBit,
			expectedCommitWeight: input.CommitWeight,
		})
	})
	t.Run("anchors", func(t *testing.T) {
		testForceClose(t, &forceCloseTestCase{
			chanType: channeldb.SingleFunderTweaklessBit |
				channeldb.AnchorOutputsBit,
			expectedCommitWeight: input.AnchorCommitWeight,
			anchorAmt:            AnchorSize * 2,
		})
	})
	t.Run("taproot", func(t *testing.T) {
		testForceClose(t, &forceCloseTestCase{
			chanType: channeldb.SingleFunderTweaklessBit |
				channeldb.AnchorOutputsBit |
				channeldb.SimpleTaprootFeatureBit,
			expectedCommitWeight: input.TaprootCommitWeight,
			anchorAmt:            AnchorSize * 2,
		})
	})
	t.Run("taproot with tapscript root", func(t *testing.T) {
		testForceClose(t, &forceCloseTestCase{
			chanType: channeldb.SingleFunderTweaklessBit |
				channeldb.AnchorOutputsBit |
				channeldb.SimpleTaprootFeatureBit |
				channeldb.TapscriptRootBit,
			expectedCommitWeight: input.TaprootCommitWeight,
			anchorAmt:            AnchorSize * 2,
		})
	})
}

type forceCloseTestCase struct {
	chanType             channeldb.ChannelType
	expectedCommitWeight lntypes.WeightUnit
	anchorAmt            btcutil.Amount
}

func testForceClose(t *testing.T, testCase *forceCloseTestCase) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, testCase.chanType,
	)
	require.NoError(t, err, "unable to create test channels")

	bobAmount := bobChannel.channelState.LocalCommitment.LocalBalance

	// First, we'll add an outgoing HTLC from Alice to Bob, such that it
	// will still be present within the broadcast commitment transaction.
	// We'll ensure that the HTLC amount is above Alice's dust limit.
	htlcAmount := lnwire.NewMSatFromSatoshis(20000)
	htlcAlice, _ := createHTLC(0, htlcAmount)
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlcAlice, nil)

	// We'll also a distinct HTLC from Bob -> Alice. This way, Alice will
	// have both an incoming and outgoing HTLC on her commitment
	// transaction.
	htlcBob, preimageBob := createHTLC(0, htlcAmount)
	addAndReceiveHTLC(t, bobChannel, aliceChannel, htlcBob, nil)

	// Next, we'll perform two state transitions to ensure that both HTLC's
	// get fully locked-in.
	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("Can't update the channel state: %v", err)
	}
	if err := ForceStateTransition(bobChannel, aliceChannel); err != nil {
		t.Fatalf("Can't update the channel state: %v", err)
	}

	// With the cache populated, we'll now attempt the force close
	// initiated by Alice.
	closeSummary, err := aliceChannel.ForceClose()
	require.NoError(t, err, "unable to force close channel")

	// Alice should detect that she can sweep the outgoing HTLC after a
	// timeout, but also that she's able to sweep in incoming HTLC Bob sent
	// her.
	if len(closeSummary.HtlcResolutions.OutgoingHTLCs) != 1 {
		t.Fatalf("alice out htlc resolutions not populated: expected %v "+
			"htlcs, got %v htlcs",
			1, len(closeSummary.HtlcResolutions.OutgoingHTLCs))
	}
	if len(closeSummary.HtlcResolutions.IncomingHTLCs) != 1 {
		t.Fatalf("alice in htlc resolutions not populated: expected %v "+
			"htlcs, got %v htlcs",
			1, len(closeSummary.HtlcResolutions.IncomingHTLCs))
	}

	// Verify the anchor resolutions for the anchor commitment format.
	if testCase.chanType.HasAnchors() {
		// Check the close summary resolution.
		anchorRes := closeSummary.AnchorResolution
		if anchorRes == nil {
			t.Fatal("expected anchor resolution")
		}
		if anchorRes.CommitAnchor.Hash != closeSummary.CloseTx.TxHash() {
			t.Fatal("commit tx not referenced by anchor res")
		}
		if anchorRes.AnchorSignDescriptor.Output.Value !=
			int64(AnchorSize) {

			t.Fatal("unexpected anchor size")
		}
		if anchorRes.AnchorSignDescriptor.WitnessScript == nil {
			t.Fatal("expected anchor witness script")
		}

		// Check the pre-confirmation resolutions.
		res, err := aliceChannel.NewAnchorResolutions()
		if err != nil {
			t.Fatalf("pre-confirmation resolution error: %v", err)
		}

		// Check we have the expected anchor resolutions.
		require.NotNil(t, res.Local, "expected local anchor resolution")
		require.NotNil(t,
			res.Remote, "expected remote anchor resolution",
		)
		require.Nil(t,
			res.RemotePending, "expected no anchor resolution",
		)
	}

	// The SelfOutputSignDesc should be non-nil since the output to-self is
	// non-dust.
	aliceCommitResolution := closeSummary.CommitResolution
	if aliceCommitResolution == nil {
		t.Fatalf("alice fails to include to-self output in " +
			"ForceCloseSummary")
	}

	// The rest of the close summary should have been populated properly.
	aliceDelayPoint := aliceChannel.channelState.LocalChanCfg.DelayBasePoint
	if !aliceCommitResolution.SelfOutputSignDesc.KeyDesc.PubKey.IsEqual(
		aliceDelayPoint.PubKey,
	) {
		t.Fatalf("alice incorrect pubkey in SelfOutputSignDesc")
	}

	// Factoring in the fee rate, Alice's amount should properly reflect
	// that we've added two additional HTLC to the commitment transaction.
	totalCommitWeight := testCase.expectedCommitWeight +
		(input.HTLCWeight * 2)
	feePerKw := chainfee.SatPerKWeight(
		aliceChannel.channelState.LocalCommitment.FeePerKw,
	)
	commitFee := feePerKw.FeeForWeight(totalCommitWeight)

	expectedAmount := (aliceChannel.Capacity / 2) -
		htlcAmount.ToSatoshis() - commitFee - testCase.anchorAmt

	if aliceCommitResolution.SelfOutputSignDesc.Output.Value != int64(expectedAmount) {
		t.Fatalf("alice incorrect output value in SelfOutputSignDesc, "+
			"expected %v, got %v", int64(expectedAmount),
			aliceCommitResolution.SelfOutputSignDesc.Output.Value)
	}

	// Alice's listed CSV delay should also match the delay that was
	// pre-committed to at channel opening.
	if aliceCommitResolution.MaturityDelay !=
		uint32(aliceChannel.channelState.LocalChanCfg.CsvDelay) {

		t.Fatalf("alice: incorrect local CSV delay in ForceCloseSummary, "+
			"expected %v, got %v",
			aliceChannel.channelState.LocalChanCfg.CsvDelay,
			aliceCommitResolution.MaturityDelay)
	}

	// Next, we'll ensure that the second level HTLC transaction it itself
	// spendable, and also that the delivery output (with delay) itself has
	// a valid sign descriptor.
	htlcResolution := closeSummary.HtlcResolutions.OutgoingHTLCs[0]
	outHtlcIndex := htlcResolution.SignedTimeoutTx.TxIn[0].PreviousOutPoint.Index
	senderHtlcPkScript := closeSummary.CloseTx.TxOut[outHtlcIndex].PkScript

	// First, verify that the second level transaction can properly spend
	// the multi-sig clause within the output on the commitment transaction
	// that produces this HTLC.
	timeoutTx := htlcResolution.SignedTimeoutTx
	prevOutputFetcher := txscript.NewCannedPrevOutputFetcher(
		senderHtlcPkScript, int64(htlcAmount.ToSatoshis()),
	)
	hashCache := txscript.NewTxSigHashes(timeoutTx, prevOutputFetcher)
	vm, err := txscript.NewEngine(
		senderHtlcPkScript,
		timeoutTx, 0, txscript.StandardVerifyFlags, nil,
		hashCache, int64(htlcAmount.ToSatoshis()), prevOutputFetcher,
	)
	require.NoError(t, err, "unable to create engine")
	if err := vm.Execute(); err != nil {
		t.Fatalf("htlc timeout spend is invalid: %v", err)
	}

	// Next, we'll ensure that we can spend the output of the second level
	// transaction given a properly crafted sweep transaction.
	sweepTx := wire.NewMsgTx(2)
	sweepTx.AddTxIn(&wire.TxIn{
		PreviousOutPoint: wire.OutPoint{
			Hash:  htlcResolution.SignedTimeoutTx.TxHash(),
			Index: 0,
		},
	})
	sweepTx.AddTxOut(&wire.TxOut{
		PkScript: senderHtlcPkScript,
		Value:    htlcResolution.SweepSignDesc.Output.Value,
	})
	htlcResolution.SweepSignDesc.InputIndex = 0

	csvDelay := uint32(aliceChannel.channelState.LocalChanCfg.CsvDelay)
	if testCase.chanType.IsTaproot() {
		sweepTx.TxIn[0].Sequence = input.LockTimeToSequence(
			false, csvDelay,
		)
		sweepTx.TxIn[0].Witness, err = input.TaprootHtlcSpendSuccess(
			aliceChannel.Signer, &htlcResolution.SweepSignDesc,
			sweepTx, nil, nil,
		)
	} else {
		sweepTx.TxIn[0].Witness, err = input.HtlcSpendSuccess(
			aliceChannel.Signer, &htlcResolution.SweepSignDesc,
			sweepTx, csvDelay,
		)
	}
	require.NoError(t, err, "unable to gen witness for timeout output")

	// With the witness fully populated for the success spend from the
	// second-level transaction, we ensure that the scripts properly
	// validate given the information within the htlc resolution struct.
	prevOutFetcher := txscript.NewCannedPrevOutputFetcher(
		htlcResolution.SweepSignDesc.Output.PkScript,
		htlcResolution.SweepSignDesc.Output.Value,
	)
	hashCache = txscript.NewTxSigHashes(sweepTx, prevOutFetcher)
	vm, err = txscript.NewEngine(
		htlcResolution.SweepSignDesc.Output.PkScript,
		sweepTx, 0, txscript.StandardVerifyFlags, nil,
		hashCache, htlcResolution.SweepSignDesc.Output.Value,
		prevOutFetcher,
	)
	require.NoError(t, err, "unable to create engine")
	if err := vm.Execute(); err != nil {
		t.Fatalf("htlc timeout spend is invalid: %v", err)
	}

	// Finally, the txid of the commitment transaction and the one returned
	// as the closing transaction should also match.
	closeTxHash := closeSummary.CloseTx.TxHash()
	commitTxHash := aliceChannel.channelState.LocalCommitment.CommitTx.TxHash()
	if !bytes.Equal(closeTxHash[:], commitTxHash[:]) {
		t.Fatalf("alice: incorrect close transaction txid")
	}

	// We'll now perform similar set of checks to ensure that Alice is able
	// to sweep the output that Bob sent to her on-chain with knowledge of
	// the preimage.
	inHtlcResolution := closeSummary.HtlcResolutions.IncomingHTLCs[0]
	inHtlcIndex := inHtlcResolution.SignedSuccessTx.TxIn[0].PreviousOutPoint.Index
	receiverHtlcScript := closeSummary.CloseTx.TxOut[inHtlcIndex].PkScript

	// With the original pkscript located, we'll now verify that the second
	// level transaction can spend from the multi-sig out. Supply the
	// preimage manually. This is usually done by the contract resolver
	// before publication.
	successTx := inHtlcResolution.SignedSuccessTx

	// For taproot channels, the preimage goes into a slightly different
	// location.
	if testCase.chanType.IsTaproot() {
		successTx.TxIn[0].Witness[2] = preimageBob[:]
	} else {
		successTx.TxIn[0].Witness[3] = preimageBob[:]
	}

	prevOuts := txscript.NewCannedPrevOutputFetcher(
		receiverHtlcScript, int64(htlcAmount.ToSatoshis()),
	)
	hashCache = txscript.NewTxSigHashes(successTx, prevOuts)
	vm, err = txscript.NewEngine(
		receiverHtlcScript,
		successTx, 0, txscript.StandardVerifyFlags, nil,
		hashCache, int64(htlcAmount.ToSatoshis()), prevOuts,
	)
	require.NoError(t, err, "unable to create engine")
	if err := vm.Execute(); err != nil {
		t.Fatalf("htlc success spend is invalid: %v", err)
	}

	// Finally, we'll construct a transaction to spend the produced
	// second-level output with the attached SignDescriptor.
	sweepTx = wire.NewMsgTx(2)
	sweepTx.AddTxIn(&wire.TxIn{
		PreviousOutPoint: inHtlcResolution.ClaimOutpoint,
	})
	sweepTx.AddTxOut(&wire.TxOut{
		PkScript: receiverHtlcScript,
		Value:    inHtlcResolution.SweepSignDesc.Output.Value,
	})
	inHtlcResolution.SweepSignDesc.InputIndex = 0
	if testCase.chanType.IsTaproot() {
		sweepTx.TxIn[0].Sequence = input.LockTimeToSequence(
			false, csvDelay,
		)
		sweepTx.TxIn[0].Witness, err = input.TaprootHtlcSpendSuccess(
			aliceChannel.Signer, &inHtlcResolution.SweepSignDesc,
			sweepTx, nil, nil,
		)
	} else {
		sweepTx.TxIn[0].Witness, err = input.HtlcSpendSuccess(
			aliceChannel.Signer, &inHtlcResolution.SweepSignDesc,
			sweepTx,
			uint32(aliceChannel.channelState.LocalChanCfg.CsvDelay),
		)
	}
	require.NoError(t, err, "unable to gen witness for timeout output")

	// The spend we create above spending the second level HTLC output
	// should validate without any issues.
	prevOuts = txscript.NewCannedPrevOutputFetcher(
		inHtlcResolution.SweepSignDesc.Output.PkScript,
		inHtlcResolution.SweepSignDesc.Output.Value,
	)
	hashCache = txscript.NewTxSigHashes(sweepTx, prevOuts)
	vm, err = txscript.NewEngine(
		inHtlcResolution.SweepSignDesc.Output.PkScript,
		sweepTx, 0, txscript.StandardVerifyFlags, nil,
		hashCache, inHtlcResolution.SweepSignDesc.Output.Value,
		prevOuts,
	)
	require.NoError(t, err, "unable to create engine")
	if err := vm.Execute(); err != nil {
		t.Fatalf("htlc timeout spend is invalid: %v", err)
	}

	// Check the same for Bob's ForceCloseSummary.
	closeSummary, err = bobChannel.ForceClose()
	require.NoError(t, err, "unable to force close channel")
	bobCommitResolution := closeSummary.CommitResolution
	if bobCommitResolution == nil {
		t.Fatalf("bob fails to include to-self output in ForceCloseSummary")
	}
	bobDelayPoint := bobChannel.channelState.LocalChanCfg.DelayBasePoint
	if !bobCommitResolution.SelfOutputSignDesc.KeyDesc.PubKey.IsEqual(bobDelayPoint.PubKey) {
		t.Fatalf("bob incorrect pubkey in SelfOutputSignDesc")
	}
	if bobCommitResolution.SelfOutputSignDesc.Output.Value !=
		int64(bobAmount.ToSatoshis()-htlcAmount.ToSatoshis()) {

		t.Fatalf("bob incorrect output value in SelfOutputSignDesc, "+
			"expected %v, got %v",
			bobAmount.ToSatoshis(),
			int64(bobCommitResolution.SelfOutputSignDesc.Output.Value))
	}
	if bobCommitResolution.MaturityDelay !=
		uint32(bobChannel.channelState.LocalChanCfg.CsvDelay) {

		t.Fatalf("bob: incorrect local CSV delay in ForceCloseSummary, "+
			"expected %v, got %v",
			bobChannel.channelState.LocalChanCfg.CsvDelay,
			bobCommitResolution.MaturityDelay)
	}

	closeTxHash = closeSummary.CloseTx.TxHash()
	commitTxHash = bobChannel.channelState.LocalCommitment.CommitTx.TxHash()
	if !bytes.Equal(closeTxHash[:], commitTxHash[:]) {
		t.Fatalf("bob: incorrect close transaction txid")
	}

	// As we didn't add the preimage of Alice's HTLC to bob's preimage
	// cache, he should only detect that he can sweep only his outgoing
	// HTLC upon force close.
	if len(closeSummary.HtlcResolutions.OutgoingHTLCs) != 1 {
		t.Fatalf("alice out htlc resolutions not populated: expected %v "+
			"htlcs, got %v htlcs",
			1, len(closeSummary.HtlcResolutions.OutgoingHTLCs))
	}

	// Bob should recognize that the incoming HTLC is there, but the
	// preimage should be empty as he doesn't have the knowledge required
	// to sweep it.
	if len(closeSummary.HtlcResolutions.IncomingHTLCs) != 1 {
		t.Fatalf("bob in htlc resolutions not populated: expected %v "+
			"htlcs, got %v htlcs",
			1, len(closeSummary.HtlcResolutions.IncomingHTLCs))
	}
}

// TestForceCloseDustOutput tests that if either side force closes with an
// active dust output (for only a single party due to asymmetric dust values),
// then the force close summary is well crafted.
func TestForceCloseDustOutput(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// We set both node's channel reserves to 0, to make sure
	// they can create small dust outputs without going under
	// their channel reserves.
	aliceChannel.channelState.LocalChanCfg.ChanReserve = 0
	bobChannel.channelState.LocalChanCfg.ChanReserve = 0
	aliceChannel.channelState.RemoteChanCfg.ChanReserve = 0
	bobChannel.channelState.RemoteChanCfg.ChanReserve = 0

	htlcAmount := lnwire.NewMSatFromSatoshis(500)

	aliceAmount := aliceChannel.channelState.LocalCommitment.LocalBalance
	bobAmount := bobChannel.channelState.LocalCommitment.LocalBalance

	// Have Bobs' to-self output be below her dust limit and check
	// ForceCloseSummary again on both peers.
	htlc, preimage := createHTLC(0, bobAmount-htlcAmount)
	bobHtlcIndex, err := bobChannel.AddHTLC(htlc, nil)
	require.NoError(t, err, "alice unable to add htlc")
	aliceHtlcIndex, err := aliceChannel.ReceiveHTLC(htlc)
	require.NoError(t, err, "bob unable to receive htlc")
	if err := ForceStateTransition(bobChannel, aliceChannel); err != nil {
		t.Fatalf("Can't update the channel state: %v", err)
	}

	// Settle HTLC and sign new commitment.
	err = aliceChannel.SettleHTLC(preimage, aliceHtlcIndex, nil, nil, nil)
	require.NoError(t, err, "bob unable to settle inbound htlc")
	err = bobChannel.ReceiveHTLCSettle(preimage, bobHtlcIndex)
	if err != nil {
		t.Fatalf("alice unable to accept settle of outbound htlc: %v", err)
	}
	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("Can't update the channel state: %v", err)
	}

	aliceAmount = aliceChannel.channelState.LocalCommitment.LocalBalance
	bobAmount = bobChannel.channelState.LocalCommitment.RemoteBalance

	closeSummary, err := aliceChannel.ForceClose()
	require.NoError(t, err, "unable to force close channel")

	// Alice's to-self output should still be in the commitment
	// transaction.
	commitResolution := closeSummary.CommitResolution
	if commitResolution == nil {
		t.Fatalf("alice fails to include to-self output in " +
			"ForceCloseSummary")
	}
	if !commitResolution.SelfOutputSignDesc.KeyDesc.PubKey.IsEqual(
		aliceChannel.channelState.LocalChanCfg.DelayBasePoint.PubKey,
	) {
		t.Fatalf("alice incorrect pubkey in SelfOutputSignDesc")
	}
	if commitResolution.SelfOutputSignDesc.Output.Value !=
		int64(aliceAmount.ToSatoshis()) {
		t.Fatalf("alice incorrect output value in SelfOutputSignDesc, "+
			"expected %v, got %v",
			aliceChannel.channelState.LocalCommitment.LocalBalance.ToSatoshis(),
			commitResolution.SelfOutputSignDesc.Output.Value)
	}

	if commitResolution.MaturityDelay !=
		uint32(aliceChannel.channelState.LocalChanCfg.CsvDelay) {
		t.Fatalf("alice: incorrect local CSV delay in ForceCloseSummary, "+
			"expected %v, got %v",
			aliceChannel.channelState.LocalChanCfg.CsvDelay,
			commitResolution.MaturityDelay)
	}

	closeTxHash := closeSummary.CloseTx.TxHash()
	commitTxHash := aliceChannel.channelState.LocalCommitment.CommitTx.TxHash()
	if !bytes.Equal(closeTxHash[:], commitTxHash[:]) {
		t.Fatalf("alice: incorrect close transaction txid")
	}

	closeSummary, err = bobChannel.ForceClose()
	require.NoError(t, err, "unable to force close channel")

	// Bob's to-self output is below Bob's dust value and should be
	// reflected in the ForceCloseSummary.
	commitResolution = closeSummary.CommitResolution
	if commitResolution != nil {
		t.Fatalf("bob incorrectly includes to-self output in " +
			"ForceCloseSummary")
	}

	closeTxHash = closeSummary.CloseTx.TxHash()
	commitTxHash = bobChannel.channelState.LocalCommitment.CommitTx.TxHash()
	if !bytes.Equal(closeTxHash[:], commitTxHash[:]) {
		t.Fatalf("bob: incorrect close transaction txid")
	}
}

// TestDustHTLCFees checks that fees are calculated correctly when HTLCs fall
// below the nodes' dust limit. In these cases, the amount of the dust HTLCs
// should be applied to the commitment transaction fee.
func TestDustHTLCFees(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	aliceStartingBalance := aliceChannel.channelState.LocalCommitment.LocalBalance

	// This HTLC amount should be lower than the dust limits of both nodes.
	htlcAmount := lnwire.NewMSatFromSatoshis(100)
	htlc, _ := createHTLC(0, htlcAmount)
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)
	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("Can't update the channel state: %v", err)
	}

	// After the transition, we'll ensure that we performed fee accounting
	// properly. Namely, the local+remote+commitfee values should add up to
	// the total capacity of the channel. This same should hold for both
	// sides.
	totalSatoshisAlice := (aliceChannel.channelState.LocalCommitment.LocalBalance +
		aliceChannel.channelState.LocalCommitment.RemoteBalance +
		lnwire.NewMSatFromSatoshis(aliceChannel.channelState.LocalCommitment.CommitFee))
	if totalSatoshisAlice+htlcAmount != lnwire.NewMSatFromSatoshis(aliceChannel.Capacity) {
		t.Fatalf("alice's funds leaked: total satoshis are %v, but channel "+
			"capacity is %v", int64(totalSatoshisAlice),
			int64(aliceChannel.Capacity))
	}
	totalSatoshisBob := (bobChannel.channelState.LocalCommitment.LocalBalance +
		bobChannel.channelState.LocalCommitment.RemoteBalance +
		lnwire.NewMSatFromSatoshis(bobChannel.channelState.LocalCommitment.CommitFee))
	if totalSatoshisBob+htlcAmount != lnwire.NewMSatFromSatoshis(bobChannel.Capacity) {
		t.Fatalf("bob's funds leaked: total satoshis are %v, but channel "+
			"capacity is %v", int64(totalSatoshisBob),
			int64(bobChannel.Capacity))
	}

	// The commitment fee paid should be the same, as there have been no
	// new material outputs added.
	defaultFee := calcStaticFee(channeldb.SingleFunderTweaklessBit, 0)
	if aliceChannel.channelState.LocalCommitment.CommitFee != defaultFee {
		t.Fatalf("dust htlc amounts not subtracted from commitment fee "+
			"expected %v, got %v", defaultFee,
			aliceChannel.channelState.LocalCommitment.CommitFee)
	}
	if bobChannel.channelState.LocalCommitment.CommitFee != defaultFee {
		t.Fatalf("dust htlc amounts not subtracted from commitment fee "+
			"expected %v, got %v", defaultFee,
			bobChannel.channelState.LocalCommitment.CommitFee)
	}

	// Alice's final balance should reflect the HTLC deficit even though
	// the HTLC was paid to fees as it was trimmed.
	aliceEndBalance := aliceChannel.channelState.LocalCommitment.LocalBalance
	aliceExpectedBalance := aliceStartingBalance - htlcAmount
	if aliceEndBalance != aliceExpectedBalance {
		t.Fatalf("alice not credited for dust: expected %v, got %v",
			aliceExpectedBalance, aliceEndBalance)
	}
}

// TestHTLCDustLimit checks the situation in which an HTLC is larger than one
// channel participant's dust limit, but smaller than the other participant's
// dust limit. In this case, the participants' commitment chains will diverge.
// In one commitment chain, the HTLC will be added as normal, in the other
// chain, the amount of the HTLC will contribute to the fees to be paid.
func TestHTLCDustLimit(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// The amount of the HTLC should be above Alice's dust limit and below
	// Bob's dust limit.
	htlcSat := (btcutil.Amount(500) + HtlcTimeoutFee(
		aliceChannel.channelState.ChanType,
		chainfee.SatPerKWeight(
			aliceChannel.channelState.LocalCommitment.FeePerKw,
		),
	))
	htlcAmount := lnwire.NewMSatFromSatoshis(htlcSat)

	htlc, preimage := createHTLC(0, htlcAmount)
	aliceHtlcIndex, err := aliceChannel.AddHTLC(htlc, nil)
	require.NoError(t, err, "alice unable to add htlc")
	bobHtlcIndex, err := bobChannel.ReceiveHTLC(htlc)
	require.NoError(t, err, "bob unable to receive htlc")
	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("Can't update the channel state: %v", err)
	}

	// At this point, Alice's commitment transaction should have an HTLC,
	// while Bob's should not, because the value falls beneath his dust
	// limit. The amount of the HTLC should be applied to fees in Bob's
	// commitment transaction.
	aliceCommitment := aliceChannel.commitChains.Local.tip()
	if len(aliceCommitment.txn.TxOut) != 3 {
		t.Fatalf("incorrect # of outputs: expected %v, got %v",
			3, len(aliceCommitment.txn.TxOut))
	}
	bobCommitment := bobChannel.commitChains.Local.tip()
	if len(bobCommitment.txn.TxOut) != 2 {
		t.Fatalf("incorrect # of outputs: expected %v, got %v",
			2, len(bobCommitment.txn.TxOut))
	}
	defaultFee := calcStaticFee(channeldb.SingleFunderTweaklessBit, 0)
	if bobChannel.channelState.LocalCommitment.CommitFee != defaultFee {
		t.Fatalf("dust htlc amount was subtracted from commitment fee "+
			"expected %v, got %v", defaultFee,
			bobChannel.channelState.LocalCommitment.CommitFee)
	}

	// Settle HTLC and create a new commitment state.
	err = bobChannel.SettleHTLC(preimage, bobHtlcIndex, nil, nil, nil)
	require.NoError(t, err, "bob unable to settle inbound htlc")
	err = aliceChannel.ReceiveHTLCSettle(preimage, aliceHtlcIndex)
	if err != nil {
		t.Fatalf("alice unable to accept settle of outbound htlc: %v", err)
	}
	if err := ForceStateTransition(bobChannel, aliceChannel); err != nil {
		t.Fatalf("state transition error: %v", err)
	}

	// At this point, for Alice's commitment chains, the value of the HTLC
	// should have been added to Alice's balance and TotalSatoshisSent.
	commitment := aliceChannel.commitChains.Local.tip()
	if len(commitment.txn.TxOut) != 2 {
		t.Fatalf("incorrect # of outputs: expected %v, got %v",
			2, len(commitment.txn.TxOut))
	}
	if aliceChannel.channelState.TotalMSatSent != htlcAmount {
		t.Fatalf("alice satoshis sent incorrect: expected %v, got %v",
			htlcAmount, aliceChannel.channelState.TotalMSatSent)
	}
}

// TestHTLCSigNumber tests that a received commitment is only accepted if it
// comes with the exact number of valid HTLC signatures.
func TestHTLCSigNumber(t *testing.T) {
	t.Parallel()

	// createChanWithHTLC is a helper method that sets ut two channels, and
	// adds HTLCs with the passed values to the channels.
	createChanWithHTLC := func(htlcValues ...btcutil.Amount) (
		*LightningChannel, *LightningChannel) {

		// Create a test channel funded evenly with Alice having 5 BTC,
		// and Bob having 5 BTC. Alice's dustlimit is 200 sat, while
		// Bob has 1300 sat.
		aliceChannel, bobChannel, err := CreateTestChannels(
			t, channeldb.SingleFunderTweaklessBit,
		)
		if err != nil {
			t.Fatalf("unable to create test channels: %v", err)
		}

		for i, htlcSat := range htlcValues {
			htlcMsat := lnwire.NewMSatFromSatoshis(htlcSat)
			htlc, _ := createHTLC(i, htlcMsat)
			addAndReceiveHTLC(
				t, aliceChannel, bobChannel, htlc, nil,
			)
		}

		return aliceChannel, bobChannel
	}

	// Calculate two values that will be below and above Bob's dust limit.
	estimator := chainfee.NewStaticEstimator(6000, 0)
	feePerKw, err := estimator.EstimateFeePerKW(1)
	require.NoError(t, err, "unable to get fee")

	belowDust := btcutil.Amount(500) + HtlcTimeoutFee(
		channeldb.SingleFunderTweaklessBit, feePerKw,
	)
	aboveDust := btcutil.Amount(1400) + HtlcSuccessFee(
		channeldb.SingleFunderTweaklessBit, feePerKw,
	)

	// ===================================================================
	// Test that Bob will reject a commitment if Alice doesn't send enough
	// HTLC signatures.
	// ===================================================================
	aliceChannel, bobChannel := createChanWithHTLC(aboveDust, aboveDust)

	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "Error signing next commitment")

	if len(aliceNewCommit.HtlcSigs) != 2 {
		t.Fatalf("expected 2 htlc sig, instead got %v",
			len(aliceNewCommit.HtlcSigs))
	}

	// Now discard one signature from the htlcSig slice. Bob should reject
	// the commitment because of this.
	aliceNewCommitCopy := *aliceNewCommit
	aliceNewCommitCopy.HtlcSigs = aliceNewCommitCopy.HtlcSigs[1:]
	err = bobChannel.ReceiveNewCommitment(aliceNewCommitCopy.CommitSigs)
	if err == nil {
		t.Fatalf("Expected Bob to reject signatures")
	}

	// ===================================================================
	// Test that Bob will reject a commitment if Alice doesn't send any
	// HTLC signatures.
	// ===================================================================
	aliceChannel, bobChannel = createChanWithHTLC(aboveDust)

	aliceNewCommit, err = aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "Error signing next commitment")

	if len(aliceNewCommit.HtlcSigs) != 1 {
		t.Fatalf("expected 1 htlc sig, instead got %v",
			len(aliceNewCommit.HtlcSigs))
	}

	// Now just give Bob an empty htlcSig slice. He should reject the
	// commitment because of this.
	aliceCommitCopy := *aliceNewCommit.CommitSigs
	aliceCommitCopy.HtlcSigs = []lnwire.Sig{}
	err = bobChannel.ReceiveNewCommitment(&aliceCommitCopy)
	if err == nil {
		t.Fatalf("Expected Bob to reject signatures")
	}

	// ==============================================================
	// Test that sigs are not returned for HTLCs below dust limit.
	// ==============================================================
	aliceChannel, bobChannel = createChanWithHTLC(belowDust)

	aliceNewCommit, err = aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "Error signing next commitment")

	// Since the HTLC is below Bob's dust limit, Alice won't need to send
	// any signatures for this HTLC.
	if len(aliceNewCommit.HtlcSigs) != 0 {
		t.Fatalf("expected no htlc sigs, instead got %v",
			len(aliceNewCommit.HtlcSigs))
	}

	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err, "Bob failed receiving commitment")

	// ================================================================
	// Test that sigs are correctly returned for HTLCs above dust limit.
	// ================================================================
	aliceChannel, bobChannel = createChanWithHTLC(aboveDust)

	aliceNewCommit, err = aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "Error signing next commitment")

	// Since the HTLC is above Bob's dust limit, Alice should send a
	// signature for this HTLC.
	if len(aliceNewCommit.HtlcSigs) != 1 {
		t.Fatalf("expected 1 htlc sig, instead got %v",
			len(aliceNewCommit.HtlcSigs))
	}

	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err, "Bob failed receiving commitment")

	// ====================================================================
	// Test that Bob will not validate a received commitment if Alice sends
	// signatures for HTLCs below the dust limit.
	// ====================================================================
	aliceChannel, bobChannel = createChanWithHTLC(belowDust, aboveDust)

	// Alice should produce only one signature, since one HTLC is below
	// dust.
	aliceNewCommit, err = aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "Error signing next commitment")

	if len(aliceNewCommit.HtlcSigs) != 1 {
		t.Fatalf("expected 1 htlc sig, instead got %v",
			len(aliceNewCommit.HtlcSigs))
	}

	// Add an extra signature.
	aliceNewCommit.HtlcSigs = append(
		aliceNewCommit.HtlcSigs, aliceNewCommit.HtlcSigs[0],
	)

	// Bob should reject these signatures since they don't match the number
	// of HTLCs above dust.
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	if err == nil {
		t.Fatalf("Expected Bob to reject signatures")
	}
}

// TestChannelBalanceDustLimit tests the condition when the remaining balance
// for one of the channel participants is so small as to be considered dust. In
// this case, the output for that participant is removed and all funds (minus
// fees) in the commitment transaction are allocated to the remaining channel
// participant.
//
// TODO(roasbeef): test needs to be fixed after reserve limits are done
func TestChannelBalanceDustLimit(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// To allow Alice's balance to get beneath her dust limit, set the
	// channel reserve to be 0.
	aliceChannel.channelState.LocalChanCfg.ChanReserve = 0
	bobChannel.channelState.RemoteChanCfg.ChanReserve = 0

	// This amount should leave an amount larger than Alice's dust limit
	// once fees have been subtracted, but smaller than Bob's dust limit.
	// We account in fees for the HTLC we will be adding.
	defaultFee := calcStaticFee(channeldb.SingleFunderTweaklessBit, 1)
	aliceBalance := aliceChannel.channelState.LocalCommitment.LocalBalance.ToSatoshis()
	htlcSat := aliceBalance - defaultFee
	htlcSat += HtlcSuccessFee(
		aliceChannel.channelState.ChanType,
		chainfee.SatPerKWeight(
			aliceChannel.channelState.LocalCommitment.FeePerKw,
		),
	)

	htlcAmount := lnwire.NewMSatFromSatoshis(htlcSat)

	htlc, preimage := createHTLC(0, htlcAmount)

	// We need to use `addHTLC` instead of `AddHTLC` so that we do not
	// enforce the FeeBuffer on alice side.
	aliceHtlcIndex, err := aliceChannel.addHTLC(htlc, nil, NoBuffer)
	require.NoError(t, err, "alice unable to add htlc")
	bobHtlcIndex, err := bobChannel.ReceiveHTLC(htlc)
	require.NoError(t, err, "bob unable to receive htlc")
	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("state transition error: %v", err)
	}
	err = bobChannel.SettleHTLC(preimage, bobHtlcIndex, nil, nil, nil)
	require.NoError(t, err, "bob unable to settle inbound htlc")
	err = aliceChannel.ReceiveHTLCSettle(preimage, aliceHtlcIndex)
	if err != nil {
		t.Fatalf("alice unable to accept settle of outbound htlc: %v", err)
	}
	if err := ForceStateTransition(bobChannel, aliceChannel); err != nil {
		t.Fatalf("state transition error: %v", err)
	}

	// At the conclusion of this test, in Bob's commitment chains, the
	// output for Alice's balance should have been removed as dust, leaving
	// only a single output that will send the remaining funds in the
	// channel to Bob.
	commitment := bobChannel.commitChains.Local.tip()
	if len(commitment.txn.TxOut) != 1 {
		t.Fatalf("incorrect # of outputs: expected %v, got %v",
			1, len(commitment.txn.TxOut))
	}
	if aliceChannel.channelState.TotalMSatSent != htlcAmount {
		t.Fatalf("alice satoshis sent incorrect: expected %v, got %v",
			htlcAmount, aliceChannel.channelState.TotalMSatSent)
	}
}

func TestStateUpdatePersistence(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	htlcAmt := lnwire.NewMSatFromSatoshis(5000)

	var fakeOnionBlob [lnwire.OnionPacketSize]byte
	copy(fakeOnionBlob[:], bytes.Repeat([]byte{0x05}, lnwire.OnionPacketSize))

	// Alice adds 3 HTLCs to the update log, while Bob adds a single HTLC.
	var alicePreimage [32]byte
	copy(alicePreimage[:], bytes.Repeat([]byte{0xaa}, 32))
	var bobPreimage [32]byte
	copy(bobPreimage[:], bytes.Repeat([]byte{0xbb}, 32))
	for i := 0; i < 3; i++ {
		rHash := sha256.Sum256(alicePreimage[:])
		h := &lnwire.UpdateAddHTLC{
			ID:          uint64(i),
			PaymentHash: rHash,
			Amount:      htlcAmt,
			Expiry:      uint32(10),
			OnionBlob:   fakeOnionBlob,
		}

		addAndReceiveHTLC(t, aliceChannel, bobChannel, h, nil)
	}
	rHash := sha256.Sum256(bobPreimage[:])
	bobh := &lnwire.UpdateAddHTLC{
		PaymentHash: rHash,
		Amount:      htlcAmt,
		Expiry:      uint32(10),
		OnionBlob:   fakeOnionBlob,
	}
	addAndReceiveHTLC(t, bobChannel, aliceChannel, bobh, nil)

	// Also add a fee update to the update logs.
	fee := chainfee.SatPerKWeight(333)
	if err := aliceChannel.UpdateFee(fee); err != nil {
		t.Fatalf("unable to send fee update")
	}
	if err := bobChannel.ReceiveUpdateFee(fee); err != nil {
		t.Fatalf("unable to receive fee update")
	}

	// Helper method that asserts the expected number of updates are found
	// in the update logs.
	assertNumLogUpdates := func(numAliceUpdates, numBobUpdates int) {
		if aliceChannel.updateLogs.Local.Len() != numAliceUpdates {
			t.Fatalf("expected %d local updates, found %d",
				numAliceUpdates,
				aliceChannel.updateLogs.Local.Len())
		}
		if aliceChannel.updateLogs.Remote.Len() != numBobUpdates {
			t.Fatalf("expected %d remote updates, found %d",
				numBobUpdates,
				aliceChannel.updateLogs.Remote.Len())
		}

		if bobChannel.updateLogs.Local.Len() != numBobUpdates {
			t.Fatalf("expected %d local updates, found %d",
				numBobUpdates,
				bobChannel.updateLogs.Local.Len())
		}
		if bobChannel.updateLogs.Remote.Len() != numAliceUpdates {
			t.Fatalf("expected %d remote updates, found %d",
				numAliceUpdates,
				bobChannel.updateLogs.Remote.Len())
		}
	}

	// Both nodes should now have Alice's 3 Adds and 1 FeeUpdate in the
	// log, and Bob's 1 Add.
	assertNumLogUpdates(4, 1)

	// Next, Alice initiates a state transition to include the HTLC's she
	// added above in a new commitment state.
	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("unable to complete alice's state transition: %v", err)
	}

	// Since the HTLC Bob sent wasn't included in Bob's version of the
	// commitment transaction (but it was in Alice's, as he ACK'd her
	// changes before creating a new state), Bob needs to trigger another
	// state update in order to re-sync their states.
	if err := ForceStateTransition(bobChannel, aliceChannel); err != nil {
		t.Fatalf("unable to complete bob's state transition: %v", err)
	}

	// After the state transition the fee update is fully locked in, and
	// should've been removed from both channels' update logs.
	if aliceChannel.commitChains.Local.tail().feePerKw != fee {
		t.Fatalf("fee not locked in")
	}
	if bobChannel.commitChains.Local.tail().feePerKw != fee {
		t.Fatalf("fee not locked in")
	}
	assertNumLogUpdates(3, 1)

	// The latest commitment from both sides should have all the HTLCs.
	numAliceOutgoing := aliceChannel.commitChains.Local.tail().outgoingHTLCs
	numAliceIncoming := aliceChannel.commitChains.Local.tail().incomingHTLCs
	if len(numAliceOutgoing) != 3 {
		t.Fatalf("expected %v htlcs, instead got %v", 3, numAliceOutgoing)
	}
	if len(numAliceIncoming) != 1 {
		t.Fatalf("expected %v htlcs, instead got %v", 1, numAliceIncoming)
	}
	numBobOutgoing := bobChannel.commitChains.Local.tail().outgoingHTLCs
	numBobIncoming := bobChannel.commitChains.Local.tail().incomingHTLCs
	if len(numBobOutgoing) != 1 {
		t.Fatalf("expected %v htlcs, instead got %v", 1, numBobOutgoing)
	}
	if len(numBobIncoming) != 3 {
		t.Fatalf("expected %v htlcs, instead got %v", 3, numBobIncoming)
	}

	// TODO(roasbeef): also ensure signatures were stored
	//  * ensure expiry matches

	// Now fetch both of the channels created above from disk to simulate a
	// node restart with persistence.
	alicePub := aliceChannel.channelState.IdentityPub
	aliceChannels, err := aliceChannel.channelState.Db.FetchOpenChannels(
		alicePub,
	)
	require.NoError(t, err, "unable to fetch channel")
	bobPub := bobChannel.channelState.IdentityPub
	bobChannels, err := bobChannel.channelState.Db.FetchOpenChannels(bobPub)
	require.NoError(t, err, "unable to fetch channel")

	aliceChannelNew, err := NewLightningChannel(
		aliceChannel.Signer, aliceChannels[0], aliceChannel.sigPool,
	)
	require.NoError(t, err, "unable to create new channel")

	bobChannelNew, err := NewLightningChannel(
		bobChannel.Signer, bobChannels[0], bobChannel.sigPool,
	)
	require.NoError(t, err, "unable to create new channel")

	// The state update logs of the new channels and the old channels
	// should now be identical other than the height the HTLCs were added.
	if aliceChannel.updateLogs.Local.logIndex !=
		aliceChannelNew.updateLogs.Local.logIndex {

		t.Fatalf("alice log counter: expected %v, got %v",
			aliceChannel.updateLogs.Local.logIndex,
			aliceChannelNew.updateLogs.Local.logIndex)
	}
	if aliceChannel.updateLogs.Remote.logIndex !=
		aliceChannelNew.updateLogs.Remote.logIndex {

		t.Fatalf("alice log counter: expected %v, got %v",
			aliceChannel.updateLogs.Remote.logIndex,
			aliceChannelNew.updateLogs.Remote.logIndex)
	}
	if aliceChannel.updateLogs.Local.Len() !=
		aliceChannelNew.updateLogs.Local.Len() {

		t.Fatalf("alice log len: expected %v, got %v",
			aliceChannel.updateLogs.Local.Len(),
			aliceChannelNew.updateLogs.Local.Len())
	}
	if aliceChannel.updateLogs.Remote.Len() !=
		aliceChannelNew.updateLogs.Remote.Len() {

		t.Fatalf("alice log len: expected %v, got %v",
			aliceChannel.updateLogs.Remote.Len(),
			aliceChannelNew.updateLogs.Remote.Len())
	}
	if bobChannel.updateLogs.Local.logIndex !=
		bobChannelNew.updateLogs.Local.logIndex {

		t.Fatalf("bob log counter: expected %v, got %v",
			bobChannel.updateLogs.Local.logIndex,
			bobChannelNew.updateLogs.Local.logIndex)
	}
	if bobChannel.updateLogs.Remote.logIndex !=
		bobChannelNew.updateLogs.Remote.logIndex {

		t.Fatalf("bob log counter: expected %v, got %v",
			bobChannel.updateLogs.Remote.logIndex,
			bobChannelNew.updateLogs.Remote.logIndex)
	}
	if bobChannel.updateLogs.Local.Len() !=
		bobChannelNew.updateLogs.Local.Len() {

		t.Fatalf("bob log len: expected %v, got %v",
			bobChannel.updateLogs.Local.Len(),
			bobChannelNew.updateLogs.Local.Len())
	}
	if bobChannel.updateLogs.Remote.Len() !=
		bobChannelNew.updateLogs.Remote.Len() {

		t.Fatalf("bob log len: expected %v, got %v",
			bobChannel.updateLogs.Remote.Len(),
			bobChannelNew.updateLogs.Remote.Len())
	}

	// TODO(roasbeef): expand test to also ensure state revocation log has
	// proper pk scripts

	// Newly generated pkScripts for HTLCs should be the same as in the old channel.
	for _, entry := range aliceChannel.updateLogs.Local.htlcIndex {
		htlc := entry.Value
		restoredHtlc := aliceChannelNew.updateLogs.Local.lookupHtlc(
			htlc.HtlcIndex,
		)
		if !bytes.Equal(htlc.ourPkScript, restoredHtlc.ourPkScript) {
			t.Fatalf("alice ourPkScript in ourLog: expected %X, got %X",
				htlc.ourPkScript[:5], restoredHtlc.ourPkScript[:5])
		}
		if !bytes.Equal(htlc.theirPkScript, restoredHtlc.theirPkScript) {
			t.Fatalf("alice theirPkScript in ourLog: expected %X, got %X",
				htlc.theirPkScript[:5], restoredHtlc.theirPkScript[:5])
		}
	}
	for _, entry := range aliceChannel.updateLogs.Remote.htlcIndex {
		htlc := entry.Value
		restoredHtlc := aliceChannelNew.updateLogs.Remote.lookupHtlc(
			htlc.HtlcIndex,
		)
		if !bytes.Equal(htlc.ourPkScript, restoredHtlc.ourPkScript) {
			t.Fatalf("alice ourPkScript in theirLog: expected %X, got %X",
				htlc.ourPkScript[:5], restoredHtlc.ourPkScript[:5])
		}
		if !bytes.Equal(htlc.theirPkScript, restoredHtlc.theirPkScript) {
			t.Fatalf("alice theirPkScript in theirLog: expected %X, got %X",
				htlc.theirPkScript[:5], restoredHtlc.theirPkScript[:5])
		}
	}
	for _, entry := range bobChannel.updateLogs.Local.htlcIndex {
		htlc := entry.Value
		restoredHtlc := bobChannelNew.updateLogs.Local.lookupHtlc(
			htlc.HtlcIndex,
		)
		if !bytes.Equal(htlc.ourPkScript, restoredHtlc.ourPkScript) {
			t.Fatalf("bob ourPkScript in ourLog: expected %X, got %X",
				htlc.ourPkScript[:5], restoredHtlc.ourPkScript[:5])
		}
		if !bytes.Equal(htlc.theirPkScript, restoredHtlc.theirPkScript) {
			t.Fatalf("bob theirPkScript in ourLog: expected %X, got %X",
				htlc.theirPkScript[:5], restoredHtlc.theirPkScript[:5])
		}
	}
	for _, entry := range bobChannel.updateLogs.Remote.htlcIndex {
		htlc := entry.Value
		restoredHtlc := bobChannelNew.updateLogs.Remote.lookupHtlc(
			htlc.HtlcIndex,
		)
		if !bytes.Equal(htlc.ourPkScript, restoredHtlc.ourPkScript) {
			t.Fatalf("bob ourPkScript in theirLog: expected %X, got %X",
				htlc.ourPkScript[:5], restoredHtlc.ourPkScript[:5])
		}
		if !bytes.Equal(htlc.theirPkScript, restoredHtlc.theirPkScript) {
			t.Fatalf("bob theirPkScript in theirLog: expected %X, got %X",
				htlc.theirPkScript[:5], restoredHtlc.theirPkScript[:5])
		}
	}

	// Now settle all the HTLCs, then force a state update. The state
	// update should succeed as both sides have identical.
	for i := 0; i < 3; i++ {
		err := bobChannelNew.SettleHTLC(alicePreimage, uint64(i), nil, nil, nil)
		if err != nil {
			t.Fatalf("unable to settle htlc #%v: %v", i, err)
		}
		err = aliceChannelNew.ReceiveHTLCSettle(alicePreimage, uint64(i))
		if err != nil {
			t.Fatalf("unable to settle htlc#%v: %v", i, err)
		}
	}
	err = aliceChannelNew.SettleHTLC(bobPreimage, 0, nil, nil, nil)
	require.NoError(t, err, "unable to settle htlc")
	err = bobChannelNew.ReceiveHTLCSettle(bobPreimage, 0)
	require.NoError(t, err, "unable to settle htlc")

	// Similar to the two transitions above, as both Bob and Alice added
	// entries to the update log before a state transition was initiated by
	// either side, both sides are required to trigger an update in order
	// to lock in their changes.
	if err := ForceStateTransition(aliceChannelNew, bobChannelNew); err != nil {
		t.Fatalf("unable to update commitments: %v", err)
	}
	if err := ForceStateTransition(bobChannelNew, aliceChannelNew); err != nil {
		t.Fatalf("unable to update commitments: %v", err)
	}

	// The amounts transferred should been updated as per the amounts in
	// the HTLCs
	if aliceChannelNew.channelState.TotalMSatSent != htlcAmt*3 {
		t.Fatalf("expected %v alice satoshis sent, got %v",
			htlcAmt*3, aliceChannelNew.channelState.TotalMSatSent)
	}
	if aliceChannelNew.channelState.TotalMSatReceived != htlcAmt {
		t.Fatalf("expected %v alice satoshis received, got %v",
			htlcAmt, aliceChannelNew.channelState.TotalMSatReceived)
	}
	if bobChannelNew.channelState.TotalMSatSent != htlcAmt {
		t.Fatalf("expected %v bob satoshis sent, got %v",
			htlcAmt, bobChannel.channelState.TotalMSatSent)
	}
	if bobChannelNew.channelState.TotalMSatReceived != htlcAmt*3 {
		t.Fatalf("expected %v bob satoshis sent, got %v",
			htlcAmt*3, bobChannel.channelState.TotalMSatReceived)
	}

	// As a final test, we'll ensure that the HTLC counters for both sides
	// has been persisted properly. If we instruct Alice to add a new HTLC,
	// it should have an index of 3. If we instruct Bob to do the
	// same, it should have an index of 1.
	aliceHtlcIndex, err := aliceChannel.AddHTLC(bobh, nil)
	require.NoError(t, err, "unable to add htlc")
	if aliceHtlcIndex != 3 {
		t.Fatalf("wrong htlc index: expected %v, got %v", 3, aliceHtlcIndex)
	}
	bobHtlcIndex, err := bobChannel.AddHTLC(bobh, nil)
	require.NoError(t, err, "unable to add htlc")
	if bobHtlcIndex != 1 {
		t.Fatalf("wrong htlc index: expected %v, got %v", 1, aliceHtlcIndex)
	}
}

func TestCancelHTLC(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// Add a new HTLC from Alice to Bob, then trigger a new state
	// transition in order to include it in the latest state.
	htlcAmt := lnwire.NewMSatFromSatoshis(btcutil.SatoshiPerBitcoin)

	var preImage [32]byte
	copy(preImage[:], bytes.Repeat([]byte{0xaa}, 32))
	htlc := &lnwire.UpdateAddHTLC{
		PaymentHash: sha256.Sum256(preImage[:]),
		Amount:      htlcAmt,
		Expiry:      10,
	}

	aliceHtlcIndex, err := aliceChannel.AddHTLC(htlc, nil)
	require.NoError(t, err, "unable to add alice htlc")
	bobHtlcIndex, err := bobChannel.ReceiveHTLC(htlc)
	require.NoError(t, err, "unable to add bob htlc")
	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("unable to create new commitment state: %v", err)
	}

	// With the HTLC committed, Alice's balance should reflect the clearing
	// of the new HTLC.
	aliceExpectedBalance := btcutil.Amount(btcutil.SatoshiPerBitcoin*4) -
		calcStaticFee(channeldb.SingleFunderTweaklessBit, 1)
	if aliceChannel.channelState.LocalCommitment.LocalBalance.ToSatoshis() !=
		aliceExpectedBalance {
		t.Fatalf("Alice's balance is wrong: expected %v, got %v",
			aliceExpectedBalance,
			aliceChannel.channelState.LocalCommitment.LocalBalance.ToSatoshis())
	}

	// Now, with the HTLC committed on both sides, trigger a cancellation
	// from Bob to Alice, removing the HTLC.
	err = bobChannel.FailHTLC(bobHtlcIndex, []byte("failreason"), nil, nil, nil)
	require.NoError(t, err, "unable to cancel HTLC")
	err = aliceChannel.ReceiveFailHTLC(aliceHtlcIndex, []byte("bad"))
	require.NoError(t, err, "unable to recv htlc cancel")

	// Now trigger another state transition, the HTLC should now be removed
	// from both sides, with balances reflected.
	if err := ForceStateTransition(bobChannel, aliceChannel); err != nil {
		t.Fatalf("unable to create new commitment: %v", err)
	}

	// Now HTLCs should be present on the commitment transaction for either
	// side.
	if len(aliceChannel.commitChains.Local.tip().outgoingHTLCs) != 0 ||
		len(aliceChannel.commitChains.Remote.tip().outgoingHTLCs) != 0 {

		t.Fatalf("htlc's still active from alice's POV")
	}
	if len(aliceChannel.commitChains.Local.tip().incomingHTLCs) != 0 ||
		len(aliceChannel.commitChains.Remote.tip().incomingHTLCs) != 0 {

		t.Fatalf("htlc's still active from alice's POV")
	}
	if len(bobChannel.commitChains.Local.tip().outgoingHTLCs) != 0 ||
		len(bobChannel.commitChains.Remote.tip().outgoingHTLCs) != 0 {

		t.Fatalf("htlc's still active from bob's POV")
	}
	if len(bobChannel.commitChains.Local.tip().incomingHTLCs) != 0 ||
		len(bobChannel.commitChains.Remote.tip().incomingHTLCs) != 0 {

		t.Fatalf("htlc's still active from bob's POV")
	}

	expectedBalance := btcutil.Amount(btcutil.SatoshiPerBitcoin * 5)
	staticFee := calcStaticFee(channeldb.SingleFunderTweaklessBit, 0)
	if aliceChannel.channelState.LocalCommitment.LocalBalance.ToSatoshis() !=
		expectedBalance-staticFee {

		t.Fatalf("balance is wrong: expected %v, got %v",
			aliceChannel.channelState.LocalCommitment.LocalBalance.ToSatoshis(),
			expectedBalance-staticFee)
	}
	if aliceChannel.channelState.LocalCommitment.RemoteBalance.ToSatoshis() !=
		expectedBalance {

		t.Fatalf("balance is wrong: expected %v, got %v",
			aliceChannel.channelState.LocalCommitment.RemoteBalance.ToSatoshis(),
			expectedBalance)
	}
	if bobChannel.channelState.LocalCommitment.LocalBalance.ToSatoshis() !=
		expectedBalance {

		t.Fatalf("balance is wrong: expected %v, got %v",
			bobChannel.channelState.LocalCommitment.LocalBalance.ToSatoshis(),
			expectedBalance)
	}
	if bobChannel.channelState.LocalCommitment.RemoteBalance.ToSatoshis() !=
		expectedBalance-staticFee {

		t.Fatalf("balance is wrong: expected %v, got %v",
			bobChannel.channelState.LocalCommitment.RemoteBalance.ToSatoshis(),
			expectedBalance-staticFee)
	}
}

func TestCooperativeCloseDustAdherence(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	aliceFeeRate := chainfee.SatPerKWeight(
		aliceChannel.channelState.LocalCommitment.FeePerKw,
	)
	bobFeeRate := chainfee.SatPerKWeight(
		bobChannel.channelState.LocalCommitment.FeePerKw,
	)

	setDustLimit := func(dustVal btcutil.Amount) {
		aliceChannel.channelState.LocalChanCfg.DustLimit = dustVal
		aliceChannel.channelState.RemoteChanCfg.DustLimit = dustVal
		bobChannel.channelState.LocalChanCfg.DustLimit = dustVal
		bobChannel.channelState.RemoteChanCfg.DustLimit = dustVal
	}

	resetChannelState := func() {
		aliceChannel.ResetState()
		bobChannel.ResetState()
	}

	setBalances := func(aliceBalance, bobBalance lnwire.MilliSatoshi) {
		aliceChannel.channelState.LocalCommitment.LocalBalance = aliceBalance
		aliceChannel.channelState.LocalCommitment.RemoteBalance = bobBalance
		bobChannel.channelState.LocalCommitment.LocalBalance = bobBalance
		bobChannel.channelState.LocalCommitment.RemoteBalance = aliceBalance
	}

	aliceDeliveryScript := bobsPrivKey[:]
	bobDeliveryScript := testHdSeed[:]

	// We'll start be initializing the limit of both Alice and Bob to 10k
	// satoshis.
	dustLimit := btcutil.Amount(10000)
	setDustLimit(dustLimit)

	// Both sides currently have over 1 BTC settled as part of their
	// balances. As a result, performing a cooperative closure now result
	// in both sides having an output within the closure transaction.
	aliceFee := btcutil.Amount(aliceChannel.CalcFee(aliceFeeRate)) + 1000
	aliceSig, _, _, err := aliceChannel.CreateCloseProposal(
		aliceFee, aliceDeliveryScript, bobDeliveryScript,
	)
	require.NoError(t, err, "unable to close channel")

	bobFee := btcutil.Amount(bobChannel.CalcFee(bobFeeRate)) + 1000
	bobSig, _, _, err := bobChannel.CreateCloseProposal(
		bobFee, bobDeliveryScript, aliceDeliveryScript,
	)
	require.NoError(t, err, "unable to close channel")

	closeTx, _, err := bobChannel.CompleteCooperativeClose(
		bobSig, aliceSig, bobDeliveryScript, aliceDeliveryScript,
		bobFee,
	)
	require.NoError(t, err, "unable to accept channel close")

	// The closure transaction should have exactly two outputs.
	if len(closeTx.TxOut) != 2 {
		t.Fatalf("close tx has wrong number of outputs: expected %v "+
			"got %v", 2, len(closeTx.TxOut))
	}

	// We'll reset the channel states before proceeding to our next test.
	resetChannelState()

	// Next we'll modify the current balances and dust limits such that
	// Bob's current balance is _below_ his dust limit.
	aliceBal := lnwire.NewMSatFromSatoshis(btcutil.SatoshiPerBitcoin)
	bobBal := lnwire.NewMSatFromSatoshis(250)
	setBalances(aliceBal, bobBal)

	// Attempt another cooperative channel closure. It should succeed
	// without any issues.
	aliceSig, _, _, err = aliceChannel.CreateCloseProposal(
		aliceFee, aliceDeliveryScript, bobDeliveryScript,
	)
	require.NoError(t, err, "unable to close channel")

	bobSig, _, _, err = bobChannel.CreateCloseProposal(
		bobFee, bobDeliveryScript, aliceDeliveryScript,
	)
	require.NoError(t, err, "unable to close channel")

	closeTx, _, err = bobChannel.CompleteCooperativeClose(
		bobSig, aliceSig, bobDeliveryScript, aliceDeliveryScript,
		bobFee,
	)
	require.NoError(t, err, "unable to accept channel close")

	// The closure transaction should only have a single output, and that
	// output should be Alice's balance.
	if len(closeTx.TxOut) != 1 {
		t.Fatalf("close tx has wrong number of outputs: expected %v "+
			"got %v", 1, len(closeTx.TxOut))
	}
	commitFee := aliceChannel.channelState.LocalCommitment.CommitFee
	aliceExpectedBalance := aliceBal.ToSatoshis() - aliceFee + commitFee
	if closeTx.TxOut[0].Value != int64(aliceExpectedBalance) {
		t.Fatalf("alice's balance is incorrect: expected %v, got %v",
			aliceExpectedBalance,
			int64(closeTx.TxOut[0].Value))
	}

	// We'll modify the current balances and dust limits such that
	// Alice's current balance is too low to pay the proposed fee.
	setBalances(bobBal, aliceBal)
	resetChannelState()

	// Attempting to close with this fee now should fail, since Alice
	// cannot afford it.
	_, _, _, err = aliceChannel.CreateCloseProposal(
		aliceFee, aliceDeliveryScript, bobDeliveryScript,
	)
	if err == nil {
		t.Fatalf("expected error")
	}

	// Finally, we'll modify the current balances and dust limits such that
	// Alice's balance after paying the coop fee is _below_ her dust limit.
	lowBalance := lnwire.NewMSatFromSatoshis(aliceFee) + 1000
	setBalances(lowBalance, aliceBal)
	resetChannelState()

	// Our final attempt at another cooperative channel closure. It should
	// succeed without any issues.
	aliceSig, _, _, err = aliceChannel.CreateCloseProposal(
		aliceFee, aliceDeliveryScript, bobDeliveryScript,
	)
	require.NoError(t, err, "unable to close channel")

	bobSig, _, _, err = bobChannel.CreateCloseProposal(
		bobFee, bobDeliveryScript, aliceDeliveryScript,
	)
	require.NoError(t, err, "unable to close channel")

	closeTx, _, err = bobChannel.CompleteCooperativeClose(
		bobSig, aliceSig, bobDeliveryScript, aliceDeliveryScript,
		bobFee,
	)
	require.NoError(t, err, "unable to accept channel close")

	// The closure transaction should only have a single output, and that
	// output should be Bob's balance.
	if len(closeTx.TxOut) != 1 {
		t.Fatalf("close tx has wrong number of outputs: expected %v "+
			"got %v", 1, len(closeTx.TxOut))
	}
	if closeTx.TxOut[0].Value != int64(aliceBal.ToSatoshis()) {
		t.Fatalf("bob's balance is incorrect: expected %v, got %v",
			aliceBal.ToSatoshis(), closeTx.TxOut[0].Value)
	}
}

// TestUpdateFeeAdjustments tests that the state machine is able to properly
// accept valid fee changes, as well as reject any invalid fee updates.
func TestUpdateFeeAdjustments(t *testing.T) {
	t.Parallel()

	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// First, we'll grab the current base fee rate as we'll be using this
	// to make relative adjustments int he fee rate.
	baseFeeRate := aliceChannel.channelState.LocalCommitment.FeePerKw

	// We'll first try to increase the fee rate 5x, this should be able to
	// be committed without any issue.
	newFee := chainfee.SatPerKWeight(baseFeeRate * 5)

	if err := aliceChannel.UpdateFee(newFee); err != nil {
		t.Fatalf("unable to alice update fee: %v", err)
	}
	if err := bobChannel.ReceiveUpdateFee(newFee); err != nil {
		t.Fatalf("unable to bob update fee: %v", err)
	}

	// With the fee updates applied, we'll now initiate a state transition
	// to ensure the fee update is locked in.
	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("unable to create new commitment: %v", err)
	}

	// We'll now attempt to increase the fee rate 1,000,000x of the base
	// fee.  This should result in an error as Alice won't be able to pay
	// this new fee rate.
	newFee = chainfee.SatPerKWeight(baseFeeRate * 1000000)
	if err := aliceChannel.UpdateFee(newFee); err == nil {
		t.Fatalf("alice should reject the fee rate")
	}

	// Finally, we'll attempt to adjust the fee down and use a fee which is
	// smaller than the initial base fee rate. The fee application and
	// state transition should proceed without issue.
	newFee = chainfee.SatPerKWeight(baseFeeRate / 10)
	if err := aliceChannel.UpdateFee(newFee); err != nil {
		t.Fatalf("unable to alice update fee: %v", err)
	}
	if err := bobChannel.ReceiveUpdateFee(newFee); err != nil {
		t.Fatalf("unable to bob update fee: %v", err)
	}
	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("unable to create new commitment: %v", err)
	}
}

// TestUpdateFeeFail tests that the signature verification will fail if they
// fee updates are out of sync.
func TestUpdateFeeFail(t *testing.T) {
	t.Parallel()

	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// Bob receives the update, that will apply to his commitment
	// transaction.
	if err := bobChannel.ReceiveUpdateFee(333); err != nil {
		t.Fatalf("unable to apply fee update: %v", err)
	}

	// Alice sends signature for commitment that does not cover any fee
	// update.
	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "alice unable to sign commitment")

	// Bob verifies this commit, meaning that he checks that it is
	// consistent everything he has received. This should fail, since he got
	// the fee update, but Alice never sent it.
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	if err == nil {
		t.Fatalf("expected bob to fail receiving alice's signature")
	}

}

// TestUpdateFeeConcurrentSig tests that the channel can properly handle a fee
// update that it receives concurrently with signing its next commitment.
func TestUpdateFeeConcurrentSig(t *testing.T) {
	t.Parallel()

	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	paymentPreimage := bytes.Repeat([]byte{1}, 32)
	paymentHash := sha256.Sum256(paymentPreimage)
	htlc := &lnwire.UpdateAddHTLC{
		PaymentHash: paymentHash,
		Amount:      btcutil.SatoshiPerBitcoin,
		Expiry:      uint32(5),
	}

	// First Alice adds the outgoing HTLC to her local channel's state
	// update log. Then Alice sends this wire message over to Bob who
	// adds this htlc to his remote state update log.
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)

	// Simulate Alice sending update fee message to bob.
	fee := chainfee.SatPerKWeight(333)
	if err := aliceChannel.UpdateFee(fee); err != nil {
		t.Fatalf("unable to send fee update")
	}

	// Alice signs a commitment, and sends this to bob.
	aliceNewCommits, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "alice unable to sign commitment")

	// At the same time, Bob signs a commitment.
	bobNewCommits, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "bob unable to sign alice's commitment")

	// ...that Alice receives.
	err = aliceChannel.ReceiveNewCommitment(bobNewCommits.CommitSigs)
	require.NoError(t, err, "alice unable to process bob's new commitment")

	// Now let Bob receive the fee update + commitment that Alice sent.
	if err := bobChannel.ReceiveUpdateFee(fee); err != nil {
		t.Fatalf("unable to receive fee update")
	}

	// Bob receives this signature message, and verifies that it is
	// consistent with the state he had for Alice, including the received
	// HTLC and fee update.
	err = bobChannel.ReceiveNewCommitment(aliceNewCommits.CommitSigs)
	require.NoError(t, err, "bob unable to process alice's new commitment")

	if chainfee.SatPerKWeight(bobChannel.channelState.LocalCommitment.FeePerKw) == fee {
		t.Fatalf("bob's feePerKw was unexpectedly locked in")
	}

	// Bob can revoke the prior commitment he had. This should lock in the
	// fee update for him.
	_, _, _, err = bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to generate bob revocation")

	if chainfee.SatPerKWeight(bobChannel.channelState.LocalCommitment.FeePerKw) != fee {
		t.Fatalf("bob's feePerKw was not locked in")
	}
}

// TestUpdateFeeSenderCommits verifies that the state machine progresses as
// expected if we send a fee update, and then the sender of the fee update
// sends a commitment signature.
func TestUpdateFeeSenderCommits(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	paymentPreimage := bytes.Repeat([]byte{1}, 32)
	paymentHash := sha256.Sum256(paymentPreimage)
	htlc := &lnwire.UpdateAddHTLC{
		PaymentHash: paymentHash,
		Amount:      btcutil.SatoshiPerBitcoin,
		Expiry:      uint32(5),
	}

	// First Alice adds the outgoing HTLC to her local channel's state
	// update log. Then Alice sends this wire message over to Bob who
	// adds this htlc to his remote state update log.
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)

	// Simulate Alice sending update fee message to bob.
	fee := chainfee.SatPerKWeight(333)
	aliceChannel.UpdateFee(fee)
	bobChannel.ReceiveUpdateFee(fee)

	// Alice signs a commitment, which will cover everything sent to Bob
	// (the HTLC and the fee update), and everything acked by Bob (nothing
	// so far).
	aliceNewCommits, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "alice unable to sign commitment")

	// Bob receives this signature message, and verifies that it is
	// consistent with the state he had for Alice, including the received
	// HTLC and fee update.
	err = bobChannel.ReceiveNewCommitment(aliceNewCommits.CommitSigs)
	require.NoError(t, err, "bob unable to process alice's new commitment")

	if chainfee.SatPerKWeight(
		bobChannel.channelState.LocalCommitment.FeePerKw,
	) == fee {

		t.Fatalf("bob's feePerKw was unexpectedly locked in")
	}

	// Bob can revoke the prior commitment he had. This should lock in the
	// fee update for him.
	bobRevocation, _, _, err := bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to generate bob revocation")

	if chainfee.SatPerKWeight(
		bobChannel.channelState.LocalCommitment.FeePerKw,
	) != fee {

		t.Fatalf("bob's feePerKw was not locked in")
	}

	// Bob commits to all updates he has received from Alice. This includes
	// the HTLC he received, and the fee update.
	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "bob unable to sign alice's commitment")

	// Alice receives the revocation of the old one, and can now assume
	// that Bob's received everything up to the signature she sent,
	// including the HTLC and fee update.
	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err, "alice unable to process bob's revocation")

	// Alice receives new signature from Bob, and assumes this covers the
	// changes.
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err, "alice unable to process bob's new commitment")

	if chainfee.SatPerKWeight(
		aliceChannel.channelState.LocalCommitment.FeePerKw,
	) == fee {

		t.Fatalf("alice's feePerKw was unexpectedly locked in")
	}

	// Alice can revoke the old commitment, which will lock in the fee
	// update.
	aliceRevocation, _, _, err := aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to revoke alice channel")

	if chainfee.SatPerKWeight(
		aliceChannel.channelState.LocalCommitment.FeePerKw,
	) != fee {

		t.Fatalf("alice's feePerKw was not locked in")
	}

	// Bob receives revocation from Alice.
	_, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err, "bob unable to process alice's revocation")

}

// TestUpdateFeeReceiverCommits tests that the state machine progresses as
// expected if we send a fee update, and then the receiver of the fee update
// sends a commitment signature.
func TestUpdateFeeReceiverCommits(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	paymentPreimage := bytes.Repeat([]byte{1}, 32)
	paymentHash := sha256.Sum256(paymentPreimage)
	htlc := &lnwire.UpdateAddHTLC{
		PaymentHash: paymentHash,
		Amount:      btcutil.SatoshiPerBitcoin,
		Expiry:      uint32(5),
	}

	// First Alice adds the outgoing HTLC to her local channel's state
	// update log. Then Alice sends this wire message over to Bob who
	// adds this htlc to his remote state update log.
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)

	// Simulate Alice sending update fee message to bob
	fee := chainfee.SatPerKWeight(333)
	aliceChannel.UpdateFee(fee)
	bobChannel.ReceiveUpdateFee(fee)

	// Bob commits to every change he has sent since last time (none). He
	// does not commit to the received HTLC and fee update, since Alice
	// cannot know if he has received them.
	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "alice unable to sign commitment")

	// Alice receives this signature message, and verifies that it is
	// consistent with the remote state, not including any of the updates.
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err, "bob unable to process alice's new commitment")

	// Alice can revoke the prior commitment she had, this will ack
	// everything received before last commitment signature, but in this
	// case that is nothing.
	aliceRevocation, _, _, err := aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to generate bob revocation")

	// Bob receives the revocation of the old commitment
	_, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err, "alice unable to process bob's revocation")

	// Alice will sign next commitment. Since she sent the revocation, she
	// also ack'ed everything received, but in this case this is nothing.
	// Since she sent the two updates, this signature will cover those two.
	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "bob unable to sign alice's commitment")

	// Bob gets the signature for the new commitment from Alice. He assumes
	// this covers everything received from alice, including the two updates.
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err, "alice unable to process bob's new commitment")

	if chainfee.SatPerKWeight(
		bobChannel.channelState.LocalCommitment.FeePerKw,
	) == fee {

		t.Fatalf("bob's feePerKw was unexpectedly locked in")
	}

	// Bob can revoke the old commitment. This will ack what he has
	// received, including the HTLC and fee update. This will lock in the
	// fee update for bob.
	bobRevocation, _, _, err := bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to revoke alice channel")

	if chainfee.SatPerKWeight(
		bobChannel.channelState.LocalCommitment.FeePerKw,
	) != fee {

		t.Fatalf("bob's feePerKw was not locked in")
	}

	// Bob will send a new signature, which will cover what he just acked:
	// the HTLC and fee update.
	bobNewCommit, err = bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "alice unable to sign commitment")

	// Alice receives revocation from Bob, and can now be sure that Bob
	// received the two updates, and they are considered locked in.
	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err, "bob unable to process alice's revocation")

	// Alice will receive the signature from Bob, which will cover what was
	// just acked by his revocation.
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err, "alice unable to process bob's new commitment")

	if chainfee.SatPerKWeight(
		aliceChannel.channelState.LocalCommitment.FeePerKw,
	) == fee {

		t.Fatalf("alice's feePerKw was unexpectedly locked in")
	}

	// After Alice now revokes her old commitment, the fee update should
	// lock in.
	aliceRevocation, _, _, err = aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to generate bob revocation")

	if chainfee.SatPerKWeight(
		aliceChannel.channelState.LocalCommitment.FeePerKw,
	) != fee {

		t.Fatalf("Alice's feePerKw was not locked in")
	}

	// Bob receives revocation from Alice.
	_, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err, "bob unable to process alice's revocation")
}

// TestUpdateFeeReceiverSendsUpdate tests that receiving a fee update as channel
// initiator fails, and that trying to initiate fee update as non-initiation
// fails.
func TestUpdateFeeReceiverSendsUpdate(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// Since Alice is the channel initiator, she should fail when receiving
	// fee update
	fee := chainfee.SatPerKWeight(333)
	err = aliceChannel.ReceiveUpdateFee(fee)
	if err == nil {
		t.Fatalf("expected alice to fail receiving fee update")
	}

	// Similarly, initiating fee update should fail for Bob.
	err = bobChannel.UpdateFee(fee)
	if err == nil {
		t.Fatalf("expected bob to fail initiating fee update")
	}
}

// Test that if multiple update fee messages are sent consecutively, then the
// last one is the one that is being committed to.
func TestUpdateFeeMultipleUpdates(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// Simulate Alice sending update fee message to bob.
	fee1 := chainfee.SatPerKWeight(333)
	fee2 := chainfee.SatPerKWeight(333)
	fee := chainfee.SatPerKWeight(333)
	aliceChannel.UpdateFee(fee1)
	aliceChannel.UpdateFee(fee2)
	aliceChannel.UpdateFee(fee)

	// Alice signs a commitment, which will cover everything sent to Bob
	// (the HTLC and the fee update), and everything acked by Bob (nothing
	// so far).
	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "alice unable to sign commitment")

	bobChannel.ReceiveUpdateFee(fee1)
	bobChannel.ReceiveUpdateFee(fee2)
	bobChannel.ReceiveUpdateFee(fee)

	// Bob receives this signature message, and verifies that it is
	// consistent with the state he had for Alice, including the received
	// HTLC and fee update.
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err, "bob unable to process alice's new commitment")

	if chainfee.SatPerKWeight(
		bobChannel.channelState.LocalCommitment.FeePerKw,
	) == fee {

		t.Fatalf("bob's feePerKw was unexpectedly locked in")
	}

	// Alice sending more fee updates now should not mess up the old fee
	// they both committed to.
	fee3 := chainfee.SatPerKWeight(444)
	fee4 := chainfee.SatPerKWeight(555)
	fee5 := chainfee.SatPerKWeight(666)
	aliceChannel.UpdateFee(fee3)
	aliceChannel.UpdateFee(fee4)
	aliceChannel.UpdateFee(fee5)
	bobChannel.ReceiveUpdateFee(fee3)
	bobChannel.ReceiveUpdateFee(fee4)
	bobChannel.ReceiveUpdateFee(fee5)

	// Bob can revoke the prior commitment he had. This should lock in the
	// fee update for him.
	bobRevocation, _, _, err := bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to generate bob revocation")

	if chainfee.SatPerKWeight(
		bobChannel.channelState.LocalCommitment.FeePerKw,
	) != fee {

		t.Fatalf("bob's feePerKw was not locked in")
	}

	// Bob commits to all updates he has received from Alice. This includes
	// the HTLC he received, and the fee update.
	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "bob unable to sign alice's commitment")

	// Alice receives the revocation of the old one, and can now assume that
	// Bob's received everything up to the signature she sent, including the
	// HTLC and fee update.
	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err, "alice unable to process bob's revocation")

	// Alice receives new signature from Bob, and assumes this covers the
	// changes.
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	if err != nil {
		t.Fatalf("alice unable to process bob's new commitment: %v", err)
	}

	if chainfee.SatPerKWeight(
		aliceChannel.channelState.LocalCommitment.FeePerKw,
	) == fee {

		t.Fatalf("alice's feePerKw was unexpectedly locked in")
	}

	// Alice can revoke the old commitment, which will lock in the fee
	// update.
	aliceRevocation, _, _, err := aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to revoke alice channel")

	if chainfee.SatPerKWeight(
		aliceChannel.channelState.LocalCommitment.FeePerKw,
	) != fee {

		t.Fatalf("alice's feePerKw was not locked in")
	}

	// Bob receives revocation from Alice.
	_, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err, "bob unable to process alice's revocation")
}

// TestAddHTLCNegativeBalance tests that if enough HTLC's are added to the
// state machine to drive the balance to zero, then the next HTLC attempted to
// be added will result in an error being returned.
func TestAddHTLCNegativeBalance(t *testing.T) {
	t.Parallel()

	// We'll kick off the test by creating our channels which both are
	// loaded with 5 BTC each.
	aliceChannel, _, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// We set the channel reserve to 0, such that we can add HTLCs all the
	// way to a negative balance.
	aliceChannel.channelState.LocalChanCfg.ChanReserve = 0

	// First, we'll add 3 HTLCs of 1 BTC each to Alice's commitment.
	const numHTLCs = 3
	htlcAmt := lnwire.NewMSatFromSatoshis(btcutil.SatoshiPerBitcoin)
	for i := 0; i < numHTLCs; i++ {
		htlc, _ := createHTLC(i, htlcAmt)
		if _, err := aliceChannel.AddHTLC(htlc, nil); err != nil {
			t.Fatalf("unable to add htlc: %v", err)
		}
	}

	// Alice now has an available balance of 2 BTC. We'll add a new HTLC of
	// value 2 BTC, which should make Alice's balance negative (since she
	// has to pay a commitment fee).
	htlcAmt = lnwire.NewMSatFromSatoshis(2 * btcutil.SatoshiPerBitcoin)
	htlc, _ := createHTLC(numHTLCs+1, htlcAmt)
	_, err = aliceChannel.AddHTLC(htlc, nil)
	require.ErrorIs(t, err, ErrBelowChanReserve)
}

// assertNoChanSyncNeeded is a helper function that asserts that upon restart,
// two channels conclude that they're fully synchronized and don't need to
// retransmit any new messages.
func assertNoChanSyncNeeded(t *testing.T, aliceChannel *LightningChannel,
	bobChannel *LightningChannel) {

	_, _, line, _ := runtime.Caller(1)

	aliceChanSyncMsg, err := aliceChannel.channelState.ChanSyncMsg()
	if err != nil {
		t.Fatalf("line #%v: unable to produce chan sync msg: %v",
			line, err)
	}
	bobChanSyncMsg, err := bobChannel.channelState.ChanSyncMsg()
	if err != nil {
		t.Fatalf("line #%v: unable to produce chan sync msg: %v",
			line, err)
	}

	// For taproot channels, simulate the link/peer binding the generated
	// nonces.
	if aliceChannel.channelState.ChanType.IsTaproot() {
		aliceChannel.pendingVerificationNonce = &musig2.Nonces{
			PubNonce: aliceChanSyncMsg.LocalNonce.UnwrapOrFailV(t),
		}
		bobChannel.pendingVerificationNonce = &musig2.Nonces{
			PubNonce: bobChanSyncMsg.LocalNonce.UnwrapOrFailV(t),
		}
	}

	bobMsgsToSend, _, _, err := bobChannel.ProcessChanSyncMsg(
		ctxb, aliceChanSyncMsg,
	)
	if err != nil {
		t.Fatalf("line #%v: unable to process ChannelReestablish "+
			"msg: %v", line, err)
	}
	if len(bobMsgsToSend) != 0 {
		t.Fatalf("line #%v: bob shouldn't have to send any messages, "+
			"instead wants to send: %v", line, spew.Sdump(bobMsgsToSend))
	}

	aliceMsgsToSend, _, _, err := aliceChannel.ProcessChanSyncMsg(
		ctxb, bobChanSyncMsg,
	)
	if err != nil {
		t.Fatalf("line #%v: unable to process ChannelReestablish "+
			"msg: %v", line, err)
	}
	if len(bobMsgsToSend) != 0 {
		t.Fatalf("line #%v: alice shouldn't have to send any "+
			"messages, instead wants to send: %v", line,
			spew.Sdump(aliceMsgsToSend))
	}
}

// TestChanSyncFullySynced tests that after a successful commitment exchange,
// and a forced restart, both nodes conclude that they're fully synchronized
// and don't need to retransmit any messages.
func TestChanSyncFullySynced(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// If we exchange channel sync messages from the get-go , then both
	// sides should conclude that no further synchronization is needed.
	assertNoChanSyncNeeded(t, aliceChannel, bobChannel)

	// Next, we'll create an HTLC for Alice to extend to Bob.
	var paymentPreimage [32]byte
	copy(paymentPreimage[:], bytes.Repeat([]byte{1}, 32))
	paymentHash := sha256.Sum256(paymentPreimage[:])
	htlcAmt := lnwire.NewMSatFromSatoshis(btcutil.SatoshiPerBitcoin)
	htlc := &lnwire.UpdateAddHTLC{
		PaymentHash: paymentHash,
		Amount:      htlcAmt,
		Expiry:      uint32(5),
	}
	aliceHtlcIndex, err := aliceChannel.AddHTLC(htlc, nil)
	require.NoError(t, err, "unable to add htlc")
	bobHtlcIndex, err := bobChannel.ReceiveHTLC(htlc)
	require.NoError(t, err, "unable to recv htlc")

	// Then we'll initiate a state transition to lock in this new HTLC.
	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("unable to complete alice's state transition: %v", err)
	}

	// At this point, if both sides generate a ChannelReestablish message,
	// they should both conclude that they're fully in sync.
	assertNoChanSyncNeeded(t, aliceChannel, bobChannel)

	// If bob settles the HTLC, and then initiates a state transition, they
	// should both still think that they're in sync.
	err = bobChannel.SettleHTLC(paymentPreimage, bobHtlcIndex, nil, nil, nil)
	require.NoError(t, err, "unable to settle htlc")
	err = aliceChannel.ReceiveHTLCSettle(paymentPreimage, aliceHtlcIndex)
	require.NoError(t, err, "unable to settle htlc")

	// Next, we'll complete Bob's state transition, and assert again that
	// they think they're fully synced.
	if err := ForceStateTransition(bobChannel, aliceChannel); err != nil {
		t.Fatalf("unable to complete bob's state transition: %v", err)
	}
	assertNoChanSyncNeeded(t, aliceChannel, bobChannel)

	// Finally, if we simulate a restart on both sides, then both should
	// still conclude that they don't need to synchronize their state.
	alicePub := aliceChannel.channelState.IdentityPub
	aliceChannels, err := aliceChannel.channelState.Db.FetchOpenChannels(
		alicePub,
	)
	require.NoError(t, err, "unable to fetch channel")
	bobPub := bobChannel.channelState.IdentityPub
	bobChannels, err := bobChannel.channelState.Db.FetchOpenChannels(bobPub)
	require.NoError(t, err, "unable to fetch channel")

	aliceChannelNew, err := NewLightningChannel(
		aliceChannel.Signer, aliceChannels[0], aliceChannel.sigPool,
	)
	require.NoError(t, err, "unable to create new channel")
	bobChannelNew, err := NewLightningChannel(
		bobChannel.Signer, bobChannels[0], bobChannel.sigPool,
	)
	require.NoError(t, err, "unable to create new channel")

	assertNoChanSyncNeeded(t, aliceChannelNew, bobChannelNew)
}

// restartChannel reads the passed channel from disk, and returns a newly
// initialized instance. This simulates one party restarting and losing their
// in memory state.
func restartChannel(channelOld *LightningChannel) (*LightningChannel, error) {
	nodePub := channelOld.channelState.IdentityPub
	nodeChannels, err := channelOld.channelState.Db.FetchOpenChannels(
		nodePub,
	)
	if err != nil {
		return nil, err
	}

	channelNew, err := NewLightningChannel(
		channelOld.Signer, nodeChannels[0],
		channelOld.sigPool,
	)
	if err != nil {
		return nil, err
	}

	return channelNew, nil
}

// testChanSyncOweCommitment tests that if Bob restarts (and then Alice) before
// he receives Alice's CommitSig message, then Alice concludes that she needs
// to re-send the CommitDiff. After the diff has been sent, both nodes should
// resynchronize and be able to complete the dangling commit.
func testChanSyncOweCommitment(t *testing.T, chanType channeldb.ChannelType) {
	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(t, chanType)
	require.NoError(t, err, "unable to create test channels")

	var fakeOnionBlob [lnwire.OnionPacketSize]byte
	copy(fakeOnionBlob[:], bytes.Repeat([]byte{0x05}, lnwire.OnionPacketSize))

	// We'll start off the scenario with Bob sending 3 HTLC's to Alice in a
	// single state update.
	htlcAmt := lnwire.NewMSatFromSatoshis(20000)
	const numBobHtlcs = 3
	var bobPreimage [32]byte
	copy(bobPreimage[:], bytes.Repeat([]byte{0xbb}, 32))
	for i := 0; i < 3; i++ {
		rHash := sha256.Sum256(bobPreimage[:])
		h := &lnwire.UpdateAddHTLC{
			PaymentHash: rHash,
			Amount:      htlcAmt,
			Expiry:      uint32(10),
			OnionBlob:   fakeOnionBlob,
		}

		htlcIndex, err := bobChannel.AddHTLC(h, nil)
		if err != nil {
			t.Fatalf("unable to add bob's htlc: %v", err)
		}

		h.ID = htlcIndex
		if _, err := aliceChannel.ReceiveHTLC(h); err != nil {
			t.Fatalf("unable to recv bob's htlc: %v", err)
		}
	}

	chanID := lnwire.NewChanIDFromOutPoint(
		aliceChannel.channelState.FundingOutpoint,
	)

	// With the HTLC's applied to both update logs, we'll initiate a state
	// transition from Bob.
	if err := ForceStateTransition(bobChannel, aliceChannel); err != nil {
		t.Fatalf("unable to complete bob's state transition: %v", err)
	}

	// Next, Alice's settles all 3 HTLC's from Bob, and also adds a new
	// HTLC of her own.
	for i := 0; i < 3; i++ {
		err := aliceChannel.SettleHTLC(bobPreimage, uint64(i), nil, nil, nil)
		if err != nil {
			t.Fatalf("unable to settle htlc: %v", err)
		}
		err = bobChannel.ReceiveHTLCSettle(bobPreimage, uint64(i))
		if err != nil {
			t.Fatalf("unable to settle htlc: %v", err)
		}
	}
	var alicePreimage [32]byte
	copy(alicePreimage[:], bytes.Repeat([]byte{0xaa}, 32))
	rHash := sha256.Sum256(alicePreimage[:])
	aliceHtlc := &lnwire.UpdateAddHTLC{
		ChanID:      chanID,
		PaymentHash: rHash,
		Amount:      htlcAmt,
		Expiry:      uint32(10),
		OnionBlob:   fakeOnionBlob,
	}
	aliceHtlcIndex, err := aliceChannel.AddHTLC(aliceHtlc, nil)
	require.NoError(t, err, "unable to add alice's htlc")
	bobHtlcIndex, err := bobChannel.ReceiveHTLC(aliceHtlc)
	require.NoError(t, err, "unable to recv alice's htlc")

	// Now we'll begin the core of the test itself. Alice will extend a new
	// commitment to Bob, but the connection drops before Bob can process
	// it.
	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign commitment")

	// If this is a taproot channel, then we'll generate fresh verification
	// nonce for both sides.
	if chanType.IsTaproot() {
		_, err = aliceChannel.GenMusigNonces()
		require.NoError(t, err)
		_, err = bobChannel.GenMusigNonces()
		require.NoError(t, err)
	}

	// Bob doesn't get this message so upon reconnection, they need to
	// synchronize. Alice should conclude that she owes Bob a commitment,
	// while Bob should think he's properly synchronized.
	aliceSyncMsg, err := aliceChannel.channelState.ChanSyncMsg()
	require.NoError(t, err, "unable to produce chan sync msg")
	bobSyncMsg, err := bobChannel.channelState.ChanSyncMsg()
	require.NoError(t, err, "unable to produce chan sync msg")

	// This is a helper function that asserts Alice concludes that she
	// needs to retransmit the exact commitment that we failed to send
	// above.
	assertAliceCommitRetransmit := func() *lnwire.CommitSig {
		aliceMsgsToSend, _, _, err := aliceChannel.ProcessChanSyncMsg(
			ctxb, bobSyncMsg,
		)
		if err != nil {
			t.Fatalf("unable to process chan sync msg: %v", err)
		}
		if len(aliceMsgsToSend) != 5 {
			t.Fatalf("expected alice to send %v messages instead "+
				"will send %v: %v", 5, len(aliceMsgsToSend),
				spew.Sdump(aliceMsgsToSend))
		}

		// Each of the settle messages that Alice sent should match her
		// original intent.
		for i := 0; i < 3; i++ {
			settleMsg, ok := aliceMsgsToSend[i].(*lnwire.UpdateFulfillHTLC)
			if !ok {
				t.Fatalf("expected an HTLC settle message, "+
					"instead have %v", spew.Sdump(settleMsg))
			}
			if settleMsg.ID != uint64(i) {
				t.Fatalf("wrong ID in settle msg: expected %v, "+
					"got %v", i, settleMsg.ID)
			}
			if settleMsg.ChanID != chanID {
				t.Fatalf("incorrect chan id: expected %v, got %v",
					chanID, settleMsg.ChanID)
			}
			if settleMsg.PaymentPreimage != bobPreimage {
				t.Fatalf("wrong pre-image: expected %v, got %v",
					alicePreimage, settleMsg.PaymentPreimage)
			}
		}

		// The HTLC add message should be identical.
		if _, ok := aliceMsgsToSend[3].(*lnwire.UpdateAddHTLC); !ok {
			t.Fatalf("expected an HTLC add message, instead have %v",
				spew.Sdump(aliceMsgsToSend[3]))
		}
		if !reflect.DeepEqual(aliceHtlc, aliceMsgsToSend[3]) {
			t.Fatalf("htlc msg doesn't match exactly: "+
				"expected %v got %v", spew.Sdump(aliceHtlc),
				spew.Sdump(aliceMsgsToSend[3]))
		}

		// Next, we'll ensure that the CommitSig message exactly
		// matches what Alice originally intended to send.
		commitSigMsg, ok := aliceMsgsToSend[4].(*lnwire.CommitSig)
		if !ok {
			t.Fatalf("expected a CommitSig message, instead have %v",
				spew.Sdump(aliceMsgsToSend[4]))
		}
		if commitSigMsg.CommitSig != aliceNewCommit.CommitSig {
			t.Fatalf("commit sig msgs don't match: expected "+
				"%x got %x",
				aliceNewCommit.CommitSig,
				commitSigMsg.CommitSig)
		}
		if len(commitSigMsg.HtlcSigs) != len(aliceNewCommit.HtlcSigs) {
			t.Fatalf("wrong number of htlc sigs: expected %v, got %v",
				len(aliceNewCommit.HtlcSigs),
				len(commitSigMsg.HtlcSigs))
		}
		for i, htlcSig := range commitSigMsg.HtlcSigs {
			if !bytes.Equal(
				htlcSig.RawBytes(),
				aliceNewCommit.HtlcSigs[i].RawBytes(),
			) {

				t.Fatalf("htlc sig msgs don't match: "+
					"expected %v got %v",
					spew.Sdump(aliceNewCommit.HtlcSigs[i]),
					spew.Sdump(htlcSig))
			}
		}

		// If this is a taproot channel, then partial sig information
		// should be present in the commit sig sent over. This
		// signature will be re-regenerated, so we can't compare it
		// with the old one.
		if chanType.IsTaproot() {
			require.True(t, commitSigMsg.PartialSig.IsSome())
		}

		return commitSigMsg
	}

	// Alice should detect that she needs to re-send 5 messages: the 3
	// settles, her HTLC add, and finally her commit sig message.
	assertAliceCommitRetransmit()

	// From Bob's Pov he has nothing else to send, so he should conclude he
	// has no further action remaining.
	bobMsgsToSend, _, _, err := bobChannel.ProcessChanSyncMsg(
		ctxb, aliceSyncMsg,
	)
	require.NoError(t, err, "unable to process chan sync msg")
	if len(bobMsgsToSend) != 0 {
		t.Fatalf("expected bob to send %v messages instead will "+
			"send %v: %v", 5, len(bobMsgsToSend),
			spew.Sdump(bobMsgsToSend))
	}

	// If we restart Alice, she should still conclude that she needs to
	// send the exact same set of messages.
	aliceChannel, err = restartChannel(aliceChannel)
	require.NoError(t, err, "unable to restart alice")

	// To properly simulate a restart, we'll use the *new* signature that
	// would send in an actual p2p setting.
	aliceReCommitSig := assertAliceCommitRetransmit()

	// At this point, we should be able to resume the prior state update
	// without any issues, resulting in Alice settling the 3 htlc's, and
	// adding one of her own.
	err = bobChannel.ReceiveNewCommitment(&CommitSigs{
		CommitSig:  aliceReCommitSig.CommitSig,
		HtlcSigs:   aliceReCommitSig.HtlcSigs,
		PartialSig: aliceReCommitSig.PartialSig,
	})
	require.NoError(t, err, "bob unable to process alice's commitment")
	bobRevocation, _, _, err := bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to revoke bob commitment")
	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "bob unable to sign commitment")
	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err, "alice unable to recv revocation")
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err, "alice unable to rev bob's commitment")
	aliceRevocation, _, _, err := aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "alice unable to revoke commitment")
	_, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err, "bob unable to recv revocation")

	// At this point, we'll now assert that their log states are what we
	// expect.
	//
	// Alice's local log counter should be 4 and her HTLC index 3. She
	// should detect Bob's remote log counter as being 3 and his HTLC index
	// 3 as well.
	if aliceChannel.updateLogs.Local.logIndex != 4 {
		t.Fatalf("incorrect log index: expected %v, got %v", 4,
			aliceChannel.updateLogs.Local.logIndex)
	}
	if aliceChannel.updateLogs.Local.htlcCounter != 1 {
		t.Fatalf("incorrect htlc index: expected %v, got %v", 1,
			aliceChannel.updateLogs.Local.htlcCounter)
	}
	if aliceChannel.updateLogs.Remote.logIndex != 3 {
		t.Fatalf("incorrect log index: expected %v, got %v", 3,
			aliceChannel.updateLogs.Local.logIndex)
	}
	if aliceChannel.updateLogs.Remote.htlcCounter != 3 {
		t.Fatalf("incorrect htlc index: expected %v, got %v", 3,
			aliceChannel.updateLogs.Local.htlcCounter)
	}

	// Bob should also have the same state, but mirrored.
	if bobChannel.updateLogs.Local.logIndex != 3 {
		t.Fatalf("incorrect log index: expected %v, got %v", 3,
			bobChannel.updateLogs.Local.logIndex)
	}
	if bobChannel.updateLogs.Local.htlcCounter != 3 {
		t.Fatalf("incorrect htlc index: expected %v, got %v", 3,
			bobChannel.updateLogs.Local.htlcCounter)
	}
	if bobChannel.updateLogs.Remote.logIndex != 4 {
		t.Fatalf("incorrect log index: expected %v, got %v", 4,
			bobChannel.updateLogs.Local.logIndex)
	}
	if bobChannel.updateLogs.Remote.htlcCounter != 1 {
		t.Fatalf("incorrect htlc index: expected %v, got %v", 1,
			bobChannel.updateLogs.Local.htlcCounter)
	}

	// We'll conclude the test by having Bob settle Alice's HTLC, then
	// initiate a state transition.
	err = bobChannel.SettleHTLC(alicePreimage, bobHtlcIndex, nil, nil, nil)
	require.NoError(t, err, "unable to settle htlc")
	err = aliceChannel.ReceiveHTLCSettle(alicePreimage, aliceHtlcIndex)
	require.NoError(t, err, "unable to settle htlc")
	if err := ForceStateTransition(bobChannel, aliceChannel); err != nil {
		t.Fatalf("unable to complete bob's state transition: %v", err)
	}

	// At this point, the final balances of both parties should properly
	// reflect the amount of HTLC's sent.
	bobMsatSent := numBobHtlcs * htlcAmt
	if aliceChannel.channelState.TotalMSatSent != htlcAmt {
		t.Fatalf("wrong value for msat sent: expected %v, got %v",
			htlcAmt, aliceChannel.channelState.TotalMSatSent)
	}
	if aliceChannel.channelState.TotalMSatReceived != bobMsatSent {
		t.Fatalf("wrong value for msat recv: expected %v, got %v",
			bobMsatSent, aliceChannel.channelState.TotalMSatReceived)
	}
	if bobChannel.channelState.TotalMSatSent != bobMsatSent {
		t.Fatalf("wrong value for msat sent: expected %v, got %v",
			bobMsatSent, bobChannel.channelState.TotalMSatSent)
	}
	if bobChannel.channelState.TotalMSatReceived != htlcAmt {
		t.Fatalf("wrong value for msat recv: expected %v, got %v",
			htlcAmt, bobChannel.channelState.TotalMSatReceived)
	}
}

// TestChanSyncOweCommitment tests that if Bob restarts (and then Alice) before
// he receives Alice's CommitSig message, then Alice concludes that she needs
// to re-send the CommitDiff. After the diff has been sent, both nodes should
// resynchronize and be able to complete the dangling commit.
func TestChanSyncOweCommitment(t *testing.T) {
	t.Parallel()

	testCases := []struct {
		name     string
		chanType channeldb.ChannelType
	}{
		{
			name:     "tweakless",
			chanType: channeldb.SingleFunderTweaklessBit,
		},
		{
			name: "anchors",
			chanType: channeldb.SingleFunderTweaklessBit |
				channeldb.AnchorOutputsBit,
		},
		{
			name: "taproot",
			chanType: channeldb.SingleFunderTweaklessBit |
				channeldb.AnchorOutputsBit |
				channeldb.SimpleTaprootFeatureBit,
		},
		{
			name: "taproot with tapscript root",
			chanType: channeldb.SingleFunderTweaklessBit |
				channeldb.AnchorOutputsBit |
				channeldb.SimpleTaprootFeatureBit |
				channeldb.TapscriptRootBit,
		},
	}
	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			testChanSyncOweCommitment(t, tc.chanType)
		})
	}
}

type testSigBlob struct {
	BlobInt tlv.RecordT[tlv.TlvType65634, uint16]
}

// TestChanSyncOweCommitmentAuxSigner tests that when one party owes a
// signature after a channel reest, if an aux signer is present, then the
// signature message sent includes the additional aux sigs as extra data.
func TestChanSyncOweCommitmentAuxSigner(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	chanType := channeldb.SingleFunderTweaklessBit |
		channeldb.AnchorOutputsBit | channeldb.SimpleTaprootFeatureBit |
		channeldb.TapscriptRootBit

	aliceChannel, bobChannel, err := CreateTestChannels(t, chanType)
	require.NoError(t, err, "unable to create test channels")

	// We'll now manually attach an aux signer to Alice's channel. We'll
	// set each aux sig job to receive an instant response.
	auxSigner := NewAuxSignerMock(EmptyMockJobHandler)
	aliceChannel.auxSigner = fn.Some[AuxSigner](auxSigner)

	var fakeOnionBlob [lnwire.OnionPacketSize]byte
	copy(
		fakeOnionBlob[:],
		bytes.Repeat([]byte{0x05}, lnwire.OnionPacketSize),
	)

	// To kick things off, we'll have Alice send a single HTLC to Bob.
	htlcAmt := lnwire.NewMSatFromSatoshis(20000)
	var bobPreimage [32]byte
	copy(bobPreimage[:], bytes.Repeat([]byte{0}, 32))
	rHash := sha256.Sum256(bobPreimage[:])
	h := &lnwire.UpdateAddHTLC{
		PaymentHash: rHash,
		Amount:      htlcAmt,
		Expiry:      uint32(10),
		OnionBlob:   fakeOnionBlob,
	}

	_, err = aliceChannel.AddHTLC(h, nil)
	require.NoError(t, err, "unable to recv bob's htlc: %v", err)

	// We'll set up the mock aux signer to expect calls to PackSigs and also
	// SubmitSecondLevelSigBatch.
	var sigBlobBuf bytes.Buffer
	sigBlob := testSigBlob{
		BlobInt: tlv.NewPrimitiveRecord[tlv.TlvType65634, uint16](5),
	}
	tlvStream, err := tlv.NewStream(sigBlob.BlobInt.Record())
	require.NoError(t, err, "unable to create tlv stream")
	require.NoError(t, tlvStream.Encode(&sigBlobBuf))

	auxSigner.On(
		"SubmitSecondLevelSigBatch", mock.Anything, mock.Anything,
		mock.Anything,
	).Return(nil).Twice()
	auxSigner.On(
		"PackSigs", mock.Anything,
	).Return(
		fn.Ok(fn.Some(sigBlobBuf.Bytes())), nil,
	)

	_, err = aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign commitment")

	_, err = aliceChannel.GenMusigNonces()
	require.NoError(t, err, "unable to generate musig nonces")

	// Next we'll simulate a restart, by having Bob send over a chan sync
	// message to Alice.
	bobSyncMsg, err := bobChannel.channelState.ChanSyncMsg()
	require.NoError(t, err, "unable to produce chan sync msg")

	aliceMsgsToSend, _, _, err := aliceChannel.ProcessChanSyncMsg(
		ctxb, bobSyncMsg,
	)
	require.NoError(t, err)
	require.Len(t, aliceMsgsToSend, 2)

	// The first message should be an update add HTLC.
	require.IsType(t, &lnwire.UpdateAddHTLC{}, aliceMsgsToSend[0])

	// The second should be a commit sig message.
	sigMsg, ok := aliceMsgsToSend[1].(*lnwire.CommitSig)
	require.True(t, ok)
	require.True(t, sigMsg.PartialSig.IsSome())

	// The signature should have the CustomRecords field set.
	require.NotEmpty(t, sigMsg.CustomRecords)
}

// TestAuxSignerShutdown tests that the channel state machine gracefully handles
// a failure of the aux signer when signing a new commitment.
func TestAuxSignerShutdown(t *testing.T) {
	t.Parallel()

	// We'll kick off the test by creating our channels which both are
	// loaded with 5 BTC each.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	auxSignerShutdownErr := errors.New("aux signer shutdown")

	// We know that aux sig jobs will be checked in SignNextCommitment() in
	// ascending output index order. So we'll fail on the first job that is
	// out of order, i.e. with an output index greater than its position in
	// the submitted jobs slice. If the jobs are ordered, we'll fail on the
	// job that is at the middle of the submitted job slice.
	failAuxSigJob := func(jobs []AuxSigJob) {
		for idx, sigJob := range jobs {
			// Simulate a clean shutdown of the aux signer and send
			// an error. Skip all remaining jobs.
			isMiddleJob := idx == len(jobs)/2
			if int(sigJob.OutputIndex) > idx || isMiddleJob {
				sigJob.Resp <- AuxSigJobResp{
					Err: auxSignerShutdownErr,
				}

				return
			}

			// If the job is 'in order', send a response with no
			// error.
			sigJob.Resp <- AuxSigJobResp{}
		}
	}

	auxSigner := NewAuxSignerMock(failAuxSigJob)
	aliceChannel.auxSigner = fn.Some[AuxSigner](auxSigner)

	// Each HTLC amount is 0.01 BTC.
	htlcAmt := lnwire.NewMSatFromSatoshis(0.01 * btcutil.SatoshiPerBitcoin)

	// Create enough HTLCs to create multiple sig jobs (one job per HTLC).
	const numHTLCs = 24

	// Send the specified number of HTLCs.
	for i := 0; i < numHTLCs; i++ {
		htlc, _ := createHTLC(i, htlcAmt)
		addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)
	}

	// We'll set up the mock aux signer to expect calls to PackSigs and also
	// SubmitSecondLevelSigBatch. The direct return values for this mock aux
	// signer are nil. The expected error comes from the sig jobs being
	// passed to failAuxSigJob above, which mimics a faulty aux signer.
	var sigBlobBuf bytes.Buffer
	sigBlob := testSigBlob{
		BlobInt: tlv.NewPrimitiveRecord[tlv.TlvType65634, uint16](5),
	}
	tlvStream, err := tlv.NewStream(sigBlob.BlobInt.Record())
	require.NoError(t, err, "unable to create tlv stream")
	require.NoError(t, tlvStream.Encode(&sigBlobBuf))

	auxSigner.On(
		"SubmitSecondLevelSigBatch", mock.Anything, mock.Anything,
		mock.Anything,
	).Return(nil).Twice()
	auxSigner.On(
		"PackSigs", mock.Anything,
	).Return(
		fn.Some(sigBlobBuf.Bytes()), nil,
	)

	_, err = aliceChannel.SignNextCommitment(ctxb)
	require.ErrorIs(t, err, auxSignerShutdownErr)
}

// TestQuitDuringSignNextCommitment tests that the channel state machine can
// successfully exit on receiving a quit signal when signing a new commitment.
func TestQuitDuringSignNextCommitment(t *testing.T) {
	t.Parallel()

	// We'll kick off the test by creating our channels which both are
	// loaded with 5 BTC each.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// We'll simulate an aux signer that was started successfully, but is
	// now frozen / inactive. This could happen if the aux signer shut down
	// without sending an error on any aux sig job error channel.
	noopAuxSigJob := func(jobs []AuxSigJob) {}

	auxSigner := NewAuxSignerMock(noopAuxSigJob)
	aliceChannel.auxSigner = fn.Some[AuxSigner](auxSigner)

	// Each HTLC amount is 0.01 BTC.
	htlcAmt := lnwire.NewMSatFromSatoshis(0.01 * btcutil.SatoshiPerBitcoin)

	// Create enough HTLCs to create multiple sig jobs (one job per HTLC).
	const numHTLCs = 24

	// Send the specified number of HTLCs.
	for i := 0; i < numHTLCs; i++ {
		htlc, _ := createHTLC(i, htlcAmt)
		addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)
	}

	// We'll set up the mock aux signer to expect calls to PackSigs and also
	// SubmitSecondLevelSigBatch. The direct return values for this mock aux
	// signer are nil. The expected error comes from the behavior of
	// noopAuxSigJob above, which mimics a faulty aux signer.
	var sigBlobBuf bytes.Buffer
	sigBlob := testSigBlob{
		BlobInt: tlv.NewPrimitiveRecord[tlv.TlvType65634, uint16](5),
	}
	tlvStream, err := tlv.NewStream(sigBlob.BlobInt.Record())
	require.NoError(t, err, "unable to create tlv stream")
	require.NoError(t, tlvStream.Encode(&sigBlobBuf))

	auxSigner.On(
		"SubmitSecondLevelSigBatch", mock.Anything, mock.Anything,
		mock.Anything,
	).Return(nil).Twice()
	auxSigner.On(
		"PackSigs", mock.Anything,
	).Return(
		fn.Some(sigBlobBuf.Bytes()), nil,
	)

	quitDelay := time.Millisecond * 20
	quit, quitFunc := context.WithCancel(context.Background())

	// Alice's channel will be stuck waiting for aux sig job responses until
	// we send the quit signal. We add an explicit sleep here so that we can
	// cause a failure if we run the test with a very short timeout.
	go func() {
		time.Sleep(quitDelay)
		quitFunc()
	}()

	_, err = aliceChannel.SignNextCommitment(quit)
	require.ErrorIs(t, err, errQuit)
}

func testChanSyncOweCommitmentPendingRemote(t *testing.T,
	chanType channeldb.ChannelType) {

	// Create a test channel which will be used for the duration of this
	// unittest.
	aliceChannel, bobChannel, err := CreateTestChannels(t, chanType)
	require.NoError(t, err, "unable to create test channels")

	var fakeOnionBlob [lnwire.OnionPacketSize]byte
	copy(
		fakeOnionBlob[:],
		bytes.Repeat([]byte{0x05}, lnwire.OnionPacketSize),
	)

	// We'll start off the scenario where Bob send two htlcs to Alice in a
	// single state update.
	var preimages []lntypes.Preimage
	const numHtlcs = 2
	for id := byte(0); id < numHtlcs; id++ {
		htlcAmt := lnwire.NewMSatFromSatoshis(20000)
		var bobPreimage [32]byte
		copy(bobPreimage[:], bytes.Repeat([]byte{id}, 32))
		rHash := sha256.Sum256(bobPreimage[:])
		h := &lnwire.UpdateAddHTLC{
			PaymentHash: rHash,
			Amount:      htlcAmt,
			Expiry:      uint32(10),
			OnionBlob:   fakeOnionBlob,
		}

		htlcIndex, err := bobChannel.AddHTLC(h, nil)
		if err != nil {
			t.Fatalf("unable to add bob's htlc: %v", err)
		}

		h.ID = htlcIndex
		if _, err := aliceChannel.ReceiveHTLC(h); err != nil {
			t.Fatalf("unable to recv bob's htlc: %v", err)
		}

		preimages = append(preimages, bobPreimage)
	}

	// With the HTLCs applied to both update logs, we'll initiate a state
	// transition from Bob.
	if err := ForceStateTransition(bobChannel, aliceChannel); err != nil {
		t.Fatalf("unable to complete bob's state transition: %v", err)
	}

	// Next, Alice settles the HTLCs from Bob in distinct state updates.
	for i := 0; i < numHtlcs; i++ {
		err = aliceChannel.SettleHTLC(
			preimages[i], uint64(i), nil, nil, nil,
		)
		if err != nil {
			t.Fatalf("unable to settle htlc: %v", err)
		}
		err = bobChannel.ReceiveHTLCSettle(preimages[i], uint64(i))
		if err != nil {
			t.Fatalf("unable to settle htlc: %v", err)
		}

		aliceNewCommit, err := aliceChannel.SignNextCommitment(
			ctxb,
		)
		if err != nil {
			t.Fatalf("unable to sign commitment: %v", err)
		}
		err = bobChannel.ReceiveNewCommitment(
			aliceNewCommit.CommitSigs,
		)
		if err != nil {
			t.Fatalf("unable to receive commitment: %v", err)
		}

		// Bob revokes his current commitment. After this call
		// completes, the htlc is settled on the local commitment
		// transaction. Bob still owes Alice a signature to also settle
		// the htlc on her local commitment transaction.
		bobRevoke, _, _, err := bobChannel.RevokeCurrentCommitment()
		if err != nil {
			t.Fatalf("unable to revoke commitment: %v", err)
		}

		_, _, err = aliceChannel.ReceiveRevocation(bobRevoke)
		if err != nil {
			t.Fatalf("unable to revoke commitment: %v", err)
		}
	}

	// We restart Bob. This should have no impact on further message that
	// are generated.
	bobChannel, err = restartChannel(bobChannel)
	require.NoError(t, err, "unable to restart bob")

	// If this is a taproot channel, then since Bob just restarted, we need
	// to exchange nonces once again.
	if chanType.IsTaproot() {
		require.NoError(t, initMusigNonce(aliceChannel, bobChannel))
	}

	// Bob signs the commitment he owes.
	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign commitment")

	// This commitment is expected to contain no htlcs anymore.
	if len(bobNewCommit.HtlcSigs) != 0 {
		t.Fatalf("no htlcs expected, but got %v",
			len(bobNewCommit.HtlcSigs))
	}

	// Get Alice to revoke and trigger Bob to compact his logs.
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	if err != nil {
		t.Fatal(err)
	}
	aliceRevoke, _, _, err := aliceChannel.RevokeCurrentCommitment()
	if err != nil {
		t.Fatal(err)
	}
	_, _, err = bobChannel.ReceiveRevocation(aliceRevoke)
	if err != nil {
		t.Fatal(err)
	}
}

// TestChanSyncOweCommitmentPendingRemote asserts that local updates are applied
// to the remote commit across restarts.
func TestChanSyncOweCommitmentPendingRemote(t *testing.T) {
	t.Parallel()

	testCases := []struct {
		name     string
		chanType channeldb.ChannelType
	}{
		{
			name:     "tweakless",
			chanType: channeldb.SingleFunderTweaklessBit,
		},
		{
			name: "anchors",
			chanType: channeldb.SingleFunderTweaklessBit |
				channeldb.AnchorOutputsBit,
		},
		{
			name: "taproot",
			chanType: channeldb.SingleFunderTweaklessBit |
				channeldb.AnchorOutputsBit |
				channeldb.SimpleTaprootFeatureBit,
		},
		{
			name: "taproot with tapscript root",
			chanType: channeldb.SingleFunderTweaklessBit |
				channeldb.AnchorOutputsBit |
				channeldb.SimpleTaprootFeatureBit |
				channeldb.TapscriptRootBit,
		},
	}
	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			testChanSyncOweCommitmentPendingRemote(t, tc.chanType)
		})
	}
}

// testChanSyncOweRevocation is the internal version of
// TestChanSyncOweRevocation that is parameterized based on the type of channel
// being used in the test.
func testChanSyncOweRevocation(t *testing.T, chanType channeldb.ChannelType) {
	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(t, chanType)
	require.NoError(t, err, "unable to create test channels")

	chanID := lnwire.NewChanIDFromOutPoint(
		aliceChannel.channelState.FundingOutpoint,
	)

	// We'll start the test with Bob extending a single HTLC to Alice, and
	// then initiating a state transition.
	htlcAmt := lnwire.NewMSatFromSatoshis(20000)
	var bobPreimage [32]byte
	copy(bobPreimage[:], bytes.Repeat([]byte{0xaa}, 32))
	rHash := sha256.Sum256(bobPreimage[:])
	bobHtlc := &lnwire.UpdateAddHTLC{
		ChanID:      chanID,
		PaymentHash: rHash,
		Amount:      htlcAmt,
		Expiry:      uint32(10),
	}
	bobHtlcIndex, err := bobChannel.AddHTLC(bobHtlc, nil)
	require.NoError(t, err, "unable to add bob's htlc")
	aliceHtlcIndex, err := aliceChannel.ReceiveHTLC(bobHtlc)
	require.NoError(t, err, "unable to recv bob's htlc")
	if err := ForceStateTransition(bobChannel, aliceChannel); err != nil {
		t.Fatalf("unable to complete bob's state transition: %v", err)
	}

	// Next, Alice will settle that single HTLC, the _begin_ the start of a
	// state transition.
	err = aliceChannel.SettleHTLC(bobPreimage, aliceHtlcIndex, nil, nil, nil)
	require.NoError(t, err, "unable to settle htlc")
	err = bobChannel.ReceiveHTLCSettle(bobPreimage, bobHtlcIndex)
	require.NoError(t, err, "unable to settle htlc")

	// We'll model the state transition right up until Alice needs to send
	// her revocation message to complete the state transition.
	//
	// Alice signs the next state, then Bob receives and sends his
	// revocation message.
	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign commitment")
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err, "bob unable to process alice's commitment")

	bobRevocation, _, _, err := bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to revoke bob commitment")
	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "bob unable to sign commitment")

	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err, "alice unable to recv revocation")
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err, "alice unable to rev bob's commitment")

	// At this point, we'll simulate the connection breaking down by Bob's
	// lack of knowledge of the revocation message that Alice just sent.
	aliceRevocation, _, _, err := aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "alice unable to revoke commitment")

	// If we fetch the channel sync messages at this state, then Alice
	// should report that she owes Bob a revocation message, while Bob
	// thinks they're fully in sync.
	aliceSyncMsg, err := aliceChannel.channelState.ChanSyncMsg()
	require.NoError(t, err, "unable to produce chan sync msg")
	bobSyncMsg, err := bobChannel.channelState.ChanSyncMsg()
	require.NoError(t, err, "unable to produce chan sync msg")

	// For taproot channels, simulate the link/peer binding the generated
	// nonces.
	if chanType.IsTaproot() {
		aliceChannel.pendingVerificationNonce = &musig2.Nonces{
			PubNonce: aliceSyncMsg.LocalNonce.UnwrapOrFail(t).Val,
		}
		bobChannel.pendingVerificationNonce = &musig2.Nonces{
			PubNonce: bobSyncMsg.LocalNonce.UnwrapOrFail(t).Val,
		}
	}

	assertAliceOwesRevoke := func() {
		t.Helper()

		aliceMsgsToSend, _, _, err := aliceChannel.ProcessChanSyncMsg(
			ctxb, bobSyncMsg,
		)
		if err != nil {
			t.Fatalf("unable to process chan sync msg: %v", err)
		}
		if len(aliceMsgsToSend) != 1 {
			t.Fatalf("expected single message retransmission from Alice, "+
				"instead got %v", spew.Sdump(aliceMsgsToSend))
		}
		aliceReRevoke, ok := aliceMsgsToSend[0].(*lnwire.RevokeAndAck)
		if !ok {
			t.Fatalf("expected to retransmit revocation msg, instead "+
				"have: %v", spew.Sdump(aliceMsgsToSend[0]))
		}

		// Alice should re-send the revocation message for her prior
		// state.
		expectedRevocation, err := aliceChannel.generateRevocation(
			aliceChannel.currentHeight - 1,
		)
		if err != nil {
			t.Fatalf("unable to regenerate revocation: %v", err)
		}
		if !reflect.DeepEqual(expectedRevocation, aliceReRevoke) {
			t.Fatalf("wrong re-revocation: expected %v, got %v",
				spew.Sdump(expectedRevocation),
				spew.Sdump(aliceReRevoke))
		}
	}

	// From Bob's PoV he shouldn't think that he owes Alice any messages.
	bobMsgsToSend, _, _, err := bobChannel.ProcessChanSyncMsg(
		ctxb, aliceSyncMsg,
	)
	require.NoError(t, err, "unable to process chan sync msg")
	if len(bobMsgsToSend) != 0 {
		t.Fatalf("expected bob to not retransmit, instead has: %v",
			spew.Sdump(bobMsgsToSend))
	}

	// Alice should detect that she owes Bob a revocation message, and only
	// that single message.
	assertAliceOwesRevoke()

	// If we restart Alice, then she should still decide that she owes a
	// revocation message to Bob.
	aliceChannel, err = restartChannel(aliceChannel)
	require.NoError(t, err, "unable to restart alice")

	// For taproot channels, simulate the link/peer binding the generated
	// nonces.
	if chanType.IsTaproot() {
		aliceChannel.pendingVerificationNonce = &musig2.Nonces{
			PubNonce: aliceSyncMsg.LocalNonce.UnwrapOrFailV(t),
		}
		bobChannel.pendingVerificationNonce = &musig2.Nonces{
			PubNonce: bobSyncMsg.LocalNonce.UnwrapOrFailV(t),
		}
	}

	assertAliceOwesRevoke()

	// We'll continue by then allowing bob to process Alice's revocation
	// message.
	_, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err, "bob unable to recv revocation")

	// Finally, Alice will add an HTLC over her own such that we assert the
	// channel can continue to receive updates.
	var alicePreimage [32]byte
	copy(bobPreimage[:], bytes.Repeat([]byte{0xaa}, 32))
	rHash = sha256.Sum256(alicePreimage[:])
	aliceHtlc := &lnwire.UpdateAddHTLC{
		ChanID:      chanID,
		PaymentHash: rHash,
		Amount:      htlcAmt,
		Expiry:      uint32(10),
	}
	addAndReceiveHTLC(t, aliceChannel, bobChannel, aliceHtlc, nil)
	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("unable to complete alice's state transition: %v", err)
	}

	// At this point, both sides should detect that they're fully synced.
	assertNoChanSyncNeeded(t, aliceChannel, bobChannel)
}

// TestChanSyncOweRevocation tests that if Bob restarts (and then Alice) before
// he received Alice's RevokeAndAck message, then Alice concludes that she
// needs to re-send the RevokeAndAck. After the revocation has been sent, both
// nodes should be able to successfully complete another state transition.
func TestChanSyncOweRevocation(t *testing.T) {
	t.Parallel()

	t.Run("tweakless", func(t *testing.T) {
		testChanSyncOweRevocation(t, channeldb.SingleFunderTweaklessBit)
	})
	t.Run("taproot", func(t *testing.T) {
		taprootBits := channeldb.SimpleTaprootFeatureBit |
			channeldb.AnchorOutputsBit |
			channeldb.ZeroHtlcTxFeeBit |
			channeldb.SingleFunderTweaklessBit

		testChanSyncOweRevocation(t, taprootBits)
	})
	t.Run("taproot with tapscript root", func(t *testing.T) {
		taprootBits := channeldb.SimpleTaprootFeatureBit |
			channeldb.AnchorOutputsBit |
			channeldb.ZeroHtlcTxFeeBit |
			channeldb.SingleFunderTweaklessBit |
			channeldb.TapscriptRootBit

		testChanSyncOweRevocation(t, taprootBits)
	})
}

func testChanSyncOweRevocationAndCommit(t *testing.T,
	chanType channeldb.ChannelType) {

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(t, chanType)
	require.NoError(t, err, "unable to create test channels")

	htlcAmt := lnwire.NewMSatFromSatoshis(20000)

	// We'll kick off the test by having Bob send Alice an HTLC, then lock
	// it in with a state transition.
	var bobPreimage [32]byte
	copy(bobPreimage[:], bytes.Repeat([]byte{0xaa}, 32))
	rHash := sha256.Sum256(bobPreimage[:])
	bobHtlc := &lnwire.UpdateAddHTLC{
		PaymentHash: rHash,
		Amount:      htlcAmt,
		Expiry:      uint32(10),
	}
	bobHtlcIndex, err := bobChannel.AddHTLC(bobHtlc, nil)
	require.NoError(t, err, "unable to add bob's htlc")
	aliceHtlcIndex, err := aliceChannel.ReceiveHTLC(bobHtlc)
	require.NoError(t, err, "unable to recv bob's htlc")
	if err := ForceStateTransition(bobChannel, aliceChannel); err != nil {
		t.Fatalf("unable to complete bob's state transition: %v", err)
	}

	// Next, Alice will settle that incoming HTLC, then we'll start the
	// core of the test itself.
	err = aliceChannel.SettleHTLC(bobPreimage, aliceHtlcIndex, nil, nil, nil)
	require.NoError(t, err, "unable to settle htlc")
	err = bobChannel.ReceiveHTLCSettle(bobPreimage, bobHtlcIndex)
	require.NoError(t, err, "unable to settle htlc")

	// Progressing the exchange: Alice will send her signature, Bob will
	// receive, send a revocation and also a signature for Alice's state.
	aliceNewCommits, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign commitment")
	err = bobChannel.ReceiveNewCommitment(aliceNewCommits.CommitSigs)
	require.NoError(t, err, "bob unable to process alice's commitment")

	// Bob generates the revoke and sig message, but the messages don't
	// reach Alice before the connection dies.
	bobRevocation, _, _, err := bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to revoke bob commitment")
	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "bob unable to sign commitment")

	// If we now attempt to resync, then Alice should conclude that she
	// doesn't need any further updates, while Bob concludes that he needs
	// to re-send both his revocation and commit sig message.
	aliceSyncMsg, err := aliceChannel.channelState.ChanSyncMsg()
	require.NoError(t, err, "unable to produce chan sync msg")
	bobSyncMsg, err := bobChannel.channelState.ChanSyncMsg()
	require.NoError(t, err, "unable to produce chan sync msg")

	// For taproot channels, simulate the link/peer binding the generated
	// nonces.
	if chanType.IsTaproot() {
		aliceChannel.pendingVerificationNonce = &musig2.Nonces{
			PubNonce: aliceSyncMsg.LocalNonce.UnwrapOrFailV(t),
		}
		bobChannel.pendingVerificationNonce = &musig2.Nonces{
			PubNonce: bobSyncMsg.LocalNonce.UnwrapOrFailV(t),
		}
	}

	aliceMsgsToSend, _, _, err := aliceChannel.ProcessChanSyncMsg(
		ctxb, bobSyncMsg,
	)
	require.NoError(t, err, "unable to process chan sync msg")
	if len(aliceMsgsToSend) != 0 {
		t.Fatalf("expected alice to not retransmit, instead she's "+
			"sending: %v", spew.Sdump(aliceMsgsToSend))
	}

	assertBobSendsRevokeAndCommit := func() {
		t.Helper()

		bobMsgsToSend, _, _, err := bobChannel.ProcessChanSyncMsg(
			ctxb, aliceSyncMsg,
		)
		if err != nil {
			t.Fatalf("unable to process chan sync msg: %v", err)
		}
		if len(bobMsgsToSend) != 2 {
			t.Fatalf("expected bob to send %v messages, instead "+
				"sends: %v", 2, spew.Sdump(bobMsgsToSend))
		}
		bobReRevoke, ok := bobMsgsToSend[0].(*lnwire.RevokeAndAck)
		if !ok {
			t.Fatalf("expected bob to re-send revoke, instead "+
				"sending: %v", spew.Sdump(bobMsgsToSend[0]))
		}
		if !reflect.DeepEqual(bobReRevoke, bobRevocation) {
			t.Fatalf("revocation msgs don't match: expected %v, "+
				"got %v", bobRevocation, bobReRevoke)
		}

		bobReCommitSigMsg, ok := bobMsgsToSend[1].(*lnwire.CommitSig)
		if !ok {
			t.Fatalf("expected bob to re-send commit sig, "+
				"instead sending: %v",
				spew.Sdump(bobMsgsToSend[1]))
		}
		if bobReCommitSigMsg.CommitSig != bobNewCommit.CommitSig {
			t.Fatalf("commit sig msgs don't match: expected %x "+
				"got %x",
				bobNewCommit.CommitSigs.CommitSig,
				bobReCommitSigMsg.CommitSig)
		}
		if len(bobReCommitSigMsg.HtlcSigs) !=
			len(bobNewCommit.HtlcSigs) {

			t.Fatalf("wrong number of htlc sigs: expected %v, "+
				"got %v",
				len(bobNewCommit.HtlcSigs),
				len(bobReCommitSigMsg.HtlcSigs))
		}
		for i, htlcSig := range bobReCommitSigMsg.HtlcSigs {
			if htlcSig != bobNewCommit.HtlcSigs[i] {
				t.Fatalf("htlc sig msgs don't match: "+
					"expected %x got %x",
					htlcSig,
					bobNewCommit.HtlcSigs[i])
			}
		}

		// If this is a taproot channel, then partial sig information
		// should be present in the commit sig sent over. This
		// signature will be re-regenerated, so we can't compare it
		// with the old one.
		if chanType.IsTaproot() {
			require.True(t, bobReCommitSigMsg.PartialSig.IsSome())
		}
	}

	// We expect Bob to send exactly two messages: first his revocation
	// message to Alice, and second his original commit sig message.
	assertBobSendsRevokeAndCommit()

	// At this point we simulate the connection failing with a restart from
	// Bob. He should still re-send the exact same set of messages.
	bobChannel, err = restartChannel(bobChannel)
	require.NoError(t, err, "unable to restart channel")

	// For taproot channels, simulate the link/peer binding the generated
	// nonces.
	if chanType.IsTaproot() {
		aliceChannel.pendingVerificationNonce = &musig2.Nonces{
			PubNonce: aliceSyncMsg.LocalNonce.UnwrapOrFailV(t),
		}
		bobChannel.pendingVerificationNonce = &musig2.Nonces{
			PubNonce: bobSyncMsg.LocalNonce.UnwrapOrFailV(t),
		}
	}

	assertBobSendsRevokeAndCommit()

	// We'll now finish the state transition by having Alice process both
	// messages, and send her final revocation.
	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err, "alice unable to recv revocation")
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err, "alice unable to recv bob's commitment")
	aliceRevocation, _, _, err := aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "alice unable to revoke commitment")
	_, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err, "bob unable to recv revocation")
}

// TestChanSyncOweRevocationAndCommit tests that if Alice initiates a state
// transition with Bob and Bob sends both a RevokeAndAck and CommitSig message
// but Alice doesn't receive them before the connection dies, then he'll
// retransmit them both.
func TestChanSyncOweRevocationAndCommit(t *testing.T) {
	t.Parallel()

	t.Run("tweakless", func(t *testing.T) {
		testChanSyncOweRevocationAndCommit(
			t, channeldb.SingleFunderTweaklessBit,
		)
	})
	t.Run("taproot", func(t *testing.T) {
		taprootBits := channeldb.SimpleTaprootFeatureBit |
			channeldb.AnchorOutputsBit |
			channeldb.ZeroHtlcTxFeeBit |
			channeldb.SingleFunderTweaklessBit

		testChanSyncOweRevocationAndCommit(t, taprootBits)
	})
	t.Run("taproot with tapscript root", func(t *testing.T) {
		taprootBits := channeldb.SimpleTaprootFeatureBit |
			channeldb.AnchorOutputsBit |
			channeldb.ZeroHtlcTxFeeBit |
			channeldb.SingleFunderTweaklessBit |
			channeldb.TapscriptRootBit

		testChanSyncOweRevocationAndCommit(t, taprootBits)
	})
}

func testChanSyncOweRevocationAndCommitForceTransition(t *testing.T,
	chanType channeldb.ChannelType) {

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(t, chanType)
	require.NoError(t, err, "unable to create test channels")

	htlcAmt := lnwire.NewMSatFromSatoshis(20000)

	// We'll kick off the test by having Bob send Alice an HTLC, then lock
	// it in with a state transition.
	var bobPreimage [32]byte
	copy(bobPreimage[:], bytes.Repeat([]byte{0xaa}, 32))
	rHash := sha256.Sum256(bobPreimage[:])
	var bobHtlc [2]*lnwire.UpdateAddHTLC
	bobHtlc[0] = &lnwire.UpdateAddHTLC{
		PaymentHash: rHash,
		Amount:      htlcAmt,
		Expiry:      uint32(10),
	}
	bobHtlcIndex, err := bobChannel.AddHTLC(bobHtlc[0], nil)
	require.NoError(t, err, "unable to add bob's htlc")
	aliceHtlcIndex, err := aliceChannel.ReceiveHTLC(bobHtlc[0])
	require.NoError(t, err, "unable to recv bob's htlc")
	if err := ForceStateTransition(bobChannel, aliceChannel); err != nil {
		t.Fatalf("unable to complete bob's state transition: %v", err)
	}

	// To ensure the channel sync logic handles the case where the two
	// commit chains are at different heights, we'll add another HTLC from
	// Bob to Alice, but let Alice skip the commitment for this state
	// update.
	rHash = sha256.Sum256(bytes.Repeat([]byte{0xbb}, 32))
	bobHtlc[1] = &lnwire.UpdateAddHTLC{
		PaymentHash: rHash,
		Amount:      htlcAmt,
		Expiry:      uint32(10),
		ID:          1,
	}
	addAndReceiveHTLC(t, bobChannel, aliceChannel, bobHtlc[1], nil)

	// Bob signs the new state update, and sends the signature to Alice.
	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "bob unable to sign commitment")

	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err, "alice unable to rev bob's commitment")

	// Alice revokes her current state, but doesn't immediately send a
	// signature for Bob's updated state. Instead she will issue a new
	// update before sending a new CommitSig. This will lead to Alice's
	// local commit chain getting height > remote commit chain.
	aliceRevocation, _, _, err := aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "alice unable to revoke commitment")
	_, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err, "bob unable to recv revocation")

	// Next, Alice will settle that incoming HTLC, then we'll start the
	// core of the test itself.
	err = aliceChannel.SettleHTLC(bobPreimage, aliceHtlcIndex, nil, nil, nil)
	require.NoError(t, err, "unable to settle htlc")
	err = bobChannel.ReceiveHTLCSettle(bobPreimage, bobHtlcIndex)
	require.NoError(t, err, "unable to settle htlc")

	// Progressing the exchange: Alice will send her signature, with Bob
	// processing the new state locally.
	aliceNewCommits, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign commitment")
	err = bobChannel.ReceiveNewCommitment(aliceNewCommits.CommitSigs)
	require.NoError(t, err, "bob unable to process alice's commitment")

	// Bob then sends his revocation message, but before Alice can process
	// it (and before he scan send his CommitSig message), then connection
	// dies.
	bobRevocation, _, _, err := bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to revoke bob commitment")

	// Now if we attempt to synchronize states at this point, Alice should
	// detect that she owes nothing, while Bob should re-send both his
	// RevokeAndAck as well as his commitment message.
	aliceSyncMsg, err := aliceChannel.channelState.ChanSyncMsg()
	require.NoError(t, err, "unable to produce chan sync msg")
	bobSyncMsg, err := bobChannel.channelState.ChanSyncMsg()
	require.NoError(t, err, "unable to produce chan sync msg")

	// For taproot channels, simulate the link/peer binding the generated
	// nonces.
	if chanType.IsTaproot() {
		aliceChannel.pendingVerificationNonce = &musig2.Nonces{
			PubNonce: aliceSyncMsg.LocalNonce.UnwrapOrFailV(t),
		}
		bobChannel.pendingVerificationNonce = &musig2.Nonces{
			PubNonce: bobSyncMsg.LocalNonce.UnwrapOrFailV(t),
		}
	}

	aliceMsgsToSend, _, _, err := aliceChannel.ProcessChanSyncMsg(
		ctxb, bobSyncMsg,
	)
	require.NoError(t, err, "unable to process chan sync msg")
	if len(aliceMsgsToSend) != 0 {
		t.Fatalf("expected alice to not retransmit, instead she's "+
			"sending: %v", spew.Sdump(aliceMsgsToSend))
	}

	// If we process Alice's sync message from Bob's PoV, then he should
	// send his RevokeAndAck message again. Additionally, the CommitSig
	// message that he sends should be sufficient to finalize the state
	// transition.
	bobMsgsToSend, _, _, err := bobChannel.ProcessChanSyncMsg(
		ctxb, aliceSyncMsg,
	)
	require.NoError(t, err, "unable to process chan sync msg")
	if len(bobMsgsToSend) != 2 {
		t.Fatalf("expected bob to send %v messages, instead "+
			"sends: %v", 2, spew.Sdump(bobMsgsToSend))
	}
	bobReRevoke, ok := bobMsgsToSend[0].(*lnwire.RevokeAndAck)
	if !ok {
		t.Fatalf("expected bob to re-send revoke, instead sending: %v",
			spew.Sdump(bobMsgsToSend[0]))
	}
	if !reflect.DeepEqual(bobReRevoke, bobRevocation) {
		t.Fatalf("revocation msgs don't match: expected %v, got %v",
			bobRevocation, bobReRevoke)
	}

	// The second message should be his CommitSig message that he never
	// sent, but will send in order to force both states to synchronize.
	bobReCommitSigMsg, ok := bobMsgsToSend[1].(*lnwire.CommitSig)
	if !ok {
		t.Fatalf("expected bob to re-send commit sig, instead sending: %v",
			spew.Sdump(bobMsgsToSend[1]))
	}

	// At this point we simulate the connection failing with a restart from
	// Bob. He should still re-send the exact same set of messages.
	bobChannel, err = restartChannel(bobChannel)
	require.NoError(t, err, "unable to restart channel")
	if len(bobMsgsToSend) != 2 {
		t.Fatalf("expected bob to send %v messages, instead "+
			"sends: %v", 2, spew.Sdump(bobMsgsToSend))
	}
	bobReRevoke, ok = bobMsgsToSend[0].(*lnwire.RevokeAndAck)
	if !ok {
		t.Fatalf("expected bob to re-send revoke, instead sending: %v",
			spew.Sdump(bobMsgsToSend[0]))
	}
	bobSigMsg, ok := bobMsgsToSend[1].(*lnwire.CommitSig)
	if !ok {
		t.Fatalf("expected bob to re-send commit sig, instead sending: %v",
			spew.Sdump(bobMsgsToSend[1]))
	}
	if !reflect.DeepEqual(bobReRevoke, bobRevocation) {
		t.Fatalf("revocation msgs don't match: expected %v, got %v",
			bobRevocation, bobReRevoke)
	}
	if bobReCommitSigMsg.CommitSig != bobSigMsg.CommitSig {
		t.Fatalf("commit sig msgs don't match: expected %x got %x",
			bobSigMsg.CommitSig,
			bobReCommitSigMsg.CommitSig)
	}
	if len(bobReCommitSigMsg.HtlcSigs) != len(bobSigMsg.HtlcSigs) {
		t.Fatalf("wrong number of htlc sigs: expected %v, got %v",
			len(bobSigMsg.HtlcSigs), len(bobReCommitSigMsg.HtlcSigs))
	}
	for i, htlcSig := range bobReCommitSigMsg.HtlcSigs {
		if htlcSig != bobSigMsg.HtlcSigs[i] {
			t.Fatalf("htlc sig msgs don't match: "+
				"expected %x got %x",
				bobSigMsg.HtlcSigs[i], htlcSig)
		}
	}

	// If this is a taproot channel, then we'll also have Bob generate their
	// current nonce, and also process Alice's.
	if chanType.IsTaproot() {
		_, err = bobChannel.GenMusigNonces()
		require.NoError(t, err)

		aliceNonces, err := aliceChannel.GenMusigNonces()
		require.NoError(t, err)

		err = bobChannel.InitRemoteMusigNonces(aliceNonces)
		require.NoError(t, err)
	}

	// Now, we'll continue the exchange, sending Bob's revocation and
	// signature message to Alice, ending with Alice sending her revocation
	// message to Bob.
	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err, "alice unable to recv revocation")
	err = aliceChannel.ReceiveNewCommitment(&CommitSigs{
		CommitSig:  bobSigMsg.CommitSig,
		HtlcSigs:   bobSigMsg.HtlcSigs,
		PartialSig: bobSigMsg.PartialSig,
	})
	require.NoError(t, err, "alice unable to rev bob's commitment")
	aliceRevocation, _, _, err = aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "alice unable to revoke commitment")
	_, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err, "bob unable to recv revocation")
}

// TestChanSyncOweRevocationAndCommitForceTransition tests that if Alice
// initiates a state transition with Bob, but Alice fails to receive his
// RevokeAndAck and the connection dies before Bob sends his CommitSig message,
// then Bob will re-send her RevokeAndAck message. Bob will also send and
// _identical_ CommitSig as he detects his commitment chain is ahead of
// Alice's.
func TestChanSyncOweRevocationAndCommitForceTransition(t *testing.T) {
	t.Parallel()

	t.Run("tweakless", func(t *testing.T) {
		testChanSyncOweRevocationAndCommitForceTransition(
			t, channeldb.SingleFunderTweaklessBit,
		)
	})
	t.Run("taproot", func(t *testing.T) {
		taprootBits := channeldb.SimpleTaprootFeatureBit |
			channeldb.AnchorOutputsBit |
			channeldb.ZeroHtlcTxFeeBit |
			channeldb.SingleFunderTweaklessBit

		testChanSyncOweRevocationAndCommitForceTransition(
			t, taprootBits,
		)
	})
	t.Run("taproot with tapscript root", func(t *testing.T) {
		taprootBits := channeldb.SimpleTaprootFeatureBit |
			channeldb.AnchorOutputsBit |
			channeldb.ZeroHtlcTxFeeBit |
			channeldb.SingleFunderTweaklessBit |
			channeldb.TapscriptRootBit

		testChanSyncOweRevocationAndCommitForceTransition(
			t, taprootBits,
		)
	})
}

// TestChanSyncFailure tests the various scenarios during channel sync where we
// should be able to detect that the channels cannot be synced because of
// invalid state.
func TestChanSyncFailure(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderBit,
	)
	require.NoError(t, err, "unable to create test channels")

	htlcAmt := lnwire.NewMSatFromSatoshis(20000)
	index := byte(0)

	// advanceState is a helper method to fully advance the channel state
	// by one.
	advanceState := func() {
		t.Helper()

		// We'll kick off the test by having Bob send Alice an HTLC,
		// then lock it in with a state transition.
		var bobPreimage [32]byte
		copy(bobPreimage[:], bytes.Repeat([]byte{0xaa - index}, 32))
		rHash := sha256.Sum256(bobPreimage[:])
		bobHtlc := &lnwire.UpdateAddHTLC{
			PaymentHash: rHash,
			Amount:      htlcAmt,
			Expiry:      uint32(10),
			ID:          uint64(index),
		}
		index++

		addAndReceiveHTLC(t, bobChannel, aliceChannel, bobHtlc, nil)
		err = ForceStateTransition(bobChannel, aliceChannel)
		if err != nil {
			t.Fatalf("unable to complete bob's state "+
				"transition: %v", err)
		}
	}

	// halfAdvance is a helper method that sends a new commitment signature
	// from Alice to Bob, but doesn't make Bob revoke his current state.
	halfAdvance := func() {
		t.Helper()

		// We'll kick off the test by having Bob send Alice an HTLC,
		// then lock it in with a state transition.
		var bobPreimage [32]byte
		copy(bobPreimage[:], bytes.Repeat([]byte{0xaa - index}, 32))
		rHash := sha256.Sum256(bobPreimage[:])
		bobHtlc := &lnwire.UpdateAddHTLC{
			PaymentHash: rHash,
			Amount:      htlcAmt,
			Expiry:      uint32(10),
			ID:          uint64(index),
		}
		index++

		addAndReceiveHTLC(t, bobChannel, aliceChannel, bobHtlc, nil)

		aliceNewCommit, err := aliceChannel.SignNextCommitment(
			ctxb,
		)
		if err != nil {
			t.Fatalf("unable to sign next commit: %v", err)
		}
		err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
		if err != nil {
			t.Fatalf("unable to receive commit sig: %v", err)
		}
	}

	// assertLocalDataLoss checks that aliceOld and bobChannel detects that
	// Alice has lost state during sync.
	assertLocalDataLoss := func(aliceOld *LightningChannel) {
		t.Helper()

		aliceSyncMsg, err := aliceOld.channelState.ChanSyncMsg()
		if err != nil {
			t.Fatalf("unable to produce chan sync msg: %v", err)
		}
		bobSyncMsg, err := bobChannel.channelState.ChanSyncMsg()
		if err != nil {
			t.Fatalf("unable to produce chan sync msg: %v", err)
		}

		// Alice should detect from Bob's message that she lost state.
		_, _, _, err = aliceOld.ProcessChanSyncMsg(ctxb, bobSyncMsg)
		if _, ok := err.(*ErrCommitSyncLocalDataLoss); !ok {
			t.Fatalf("wrong error, expected "+
				"ErrCommitSyncLocalDataLoss instead got: %v",
				err)
		}

		// Bob should detect that Alice probably lost state.
		_, _, _, err = bobChannel.ProcessChanSyncMsg(
			ctxb, aliceSyncMsg,
		)
		if err != ErrCommitSyncRemoteDataLoss {
			t.Fatalf("wrong error, expected "+
				"ErrCommitSyncRemoteDataLoss instead got: %v",
				err)
		}
	}

	// clearBorkedState is a method that allows us to clear the borked
	// state that will arise after the first chan message sync. We need to
	// do this in order to be able to continue to update the commitment
	// state for our test scenarios.
	clearBorkedState := func() {
		err = aliceChannel.channelState.ClearChanStatus(
			channeldb.ChanStatusLocalDataLoss | channeldb.ChanStatusBorked,
		)
		if err != nil {
			t.Fatalf("unable to update channel state: %v", err)
		}
		err = bobChannel.channelState.ClearChanStatus(
			channeldb.ChanStatusLocalDataLoss | channeldb.ChanStatusBorked,
		)
		if err != nil {
			t.Fatalf("unable to update channel state: %v", err)
		}
	}

	// Start by advancing the state.
	advanceState()

	// They should be in sync.
	assertNoChanSyncNeeded(t, aliceChannel, bobChannel)

	// Make a copy of Alice's state from the database at this point.
	aliceOld, err := restartChannel(aliceChannel)
	require.NoError(t, err, "unable to restart channel")

	// Advance the states.
	advanceState()

	// Trying to sync up the old version of Alice's channel should detect
	// that we are out of sync.
	assertLocalDataLoss(aliceOld)

	// Make sure the up-to-date channels still are in sync.
	assertNoChanSyncNeeded(t, aliceChannel, bobChannel)

	// Clear the borked state before we attempt to advance.
	clearBorkedState()

	// Advance the state again, and do the same check.
	advanceState()
	assertNoChanSyncNeeded(t, aliceChannel, bobChannel)
	assertLocalDataLoss(aliceOld)

	// If we remove the recovery options from Bob's message, Alice cannot
	// tell if she lost state, since Bob might be lying. She still should
	// be able to detect that chains cannot be synced.
	bobSyncMsg, err := bobChannel.channelState.ChanSyncMsg()
	require.NoError(t, err, "unable to produce chan sync msg")
	bobSyncMsg.LocalUnrevokedCommitPoint = nil
	_, _, _, err = aliceOld.ProcessChanSyncMsg(ctxb, bobSyncMsg)
	if err != ErrCannotSyncCommitChains {
		t.Fatalf("wrong error, expected ErrCannotSyncCommitChains "+
			"instead got: %v", err)
	}

	// If Bob lies about the NextLocalCommitHeight, making it greater than
	// what Alice expect, she cannot tell for sure whether she lost state,
	// but should detect the desync.
	bobSyncMsg, err = bobChannel.channelState.ChanSyncMsg()
	require.NoError(t, err, "unable to produce chan sync msg")
	bobSyncMsg.NextLocalCommitHeight++
	_, _, _, err = aliceChannel.ProcessChanSyncMsg(ctxb, bobSyncMsg)
	if err != ErrCannotSyncCommitChains {
		t.Fatalf("wrong error, expected ErrCannotSyncCommitChains "+
			"instead got: %v", err)
	}

	// If Bob's NextLocalCommitHeight is lower than what Alice expects, Bob
	// probably lost state.
	bobSyncMsg, err = bobChannel.channelState.ChanSyncMsg()
	require.NoError(t, err, "unable to produce chan sync msg")
	bobSyncMsg.NextLocalCommitHeight--
	_, _, _, err = aliceChannel.ProcessChanSyncMsg(ctxb, bobSyncMsg)
	if err != ErrCommitSyncRemoteDataLoss {
		t.Fatalf("wrong error, expected ErrCommitSyncRemoteDataLoss "+
			"instead got: %v", err)
	}

	// If Alice and Bob's states are in sync, but Bob is sending the wrong
	// LocalUnrevokedCommitPoint, Alice should detect this.
	bobSyncMsg, err = bobChannel.channelState.ChanSyncMsg()
	require.NoError(t, err, "unable to produce chan sync msg")
	p := bobSyncMsg.LocalUnrevokedCommitPoint.SerializeCompressed()
	p[4] ^= 0x01
	modCommitPoint, err := btcec.ParsePubKey(p)
	require.NoError(t, err, "unable to parse pubkey")

	bobSyncMsg.LocalUnrevokedCommitPoint = modCommitPoint
	_, _, _, err = aliceChannel.ProcessChanSyncMsg(ctxb, bobSyncMsg)
	if err != ErrInvalidLocalUnrevokedCommitPoint {
		t.Fatalf("wrong error, expected "+
			"ErrInvalidLocalUnrevokedCommitPoint instead got: %v",
			err)
	}

	// Make sure the up-to-date channels still are good.
	assertNoChanSyncNeeded(t, aliceChannel, bobChannel)

	// Clear the borked state before we attempt to advance.
	clearBorkedState()

	// Finally check that Alice is also able to detect a wrong commit point
	// when there's a pending remote commit.
	halfAdvance()

	bobSyncMsg, err = bobChannel.channelState.ChanSyncMsg()
	require.NoError(t, err, "unable to produce chan sync msg")
	bobSyncMsg.LocalUnrevokedCommitPoint = modCommitPoint
	_, _, _, err = aliceChannel.ProcessChanSyncMsg(ctxb, bobSyncMsg)
	if err != ErrInvalidLocalUnrevokedCommitPoint {
		t.Fatalf("wrong error, expected "+
			"ErrInvalidLocalUnrevokedCommitPoint instead got: %v",
			err)
	}
}

// TestFeeUpdateRejectInsaneFee tests that if the initiator tries to attach a
// fee that would put them below their current reserve, then it's rejected by
// the state machine.
func TestFeeUpdateRejectInsaneFee(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, _, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// Next, we'll try to add a fee rate to Alice which is 1,000,000x her
	// starting fee rate.
	startingFeeRate := chainfee.SatPerKWeight(
		aliceChannel.channelState.LocalCommitment.FeePerKw,
	)
	newFeeRate := startingFeeRate * 1000000

	// Both Alice and Bob should reject this new fee rate as it is far too
	// large.
	if err := aliceChannel.UpdateFee(newFeeRate); err == nil {
		t.Fatalf("alice should have rejected fee update")
	}
}

// TestChannelRetransmissionFeeUpdate tests that the initiator will include any
// pending fee updates if it needs to retransmit signatures.
func TestChannelRetransmissionFeeUpdate(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// First, we'll fetch the current fee rate present within the
	// commitment transactions.
	startingFeeRate := chainfee.SatPerKWeight(
		aliceChannel.channelState.LocalCommitment.FeePerKw,
	)

	// Next, we'll start a commitment update, with Alice sending a new
	// update to double the fee rate of the commitment.
	newFeeRate := startingFeeRate * 2
	if err := aliceChannel.UpdateFee(newFeeRate); err != nil {
		t.Fatalf("unable to update fee for Alice's channel: %v", err)
	}
	if err := bobChannel.ReceiveUpdateFee(newFeeRate); err != nil {
		t.Fatalf("unable to update fee for Bob's channel: %v", err)
	}

	// Now, Alice will send a new commitment to Bob, but we'll simulate a
	// connection failure, so Bob doesn't get her signature.
	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign commitment")

	// Restart both channels to simulate a connection restart.
	aliceChannel, err = restartChannel(aliceChannel)
	require.NoError(t, err, "unable to restart alice")
	bobChannel, err = restartChannel(bobChannel)
	require.NoError(t, err, "unable to restart channel")

	// Bob doesn't get this message so upon reconnection, they need to
	// synchronize. Alice should conclude that she owes Bob a commitment,
	// while Bob should think he's properly synchronized.
	aliceSyncMsg, err := aliceChannel.channelState.ChanSyncMsg()
	require.NoError(t, err, "unable to produce chan sync msg")
	bobSyncMsg, err := bobChannel.channelState.ChanSyncMsg()
	require.NoError(t, err, "unable to produce chan sync msg")

	// Bob should detect that he doesn't need to send anything to Alice.
	bobMsgsToSend, _, _, err := bobChannel.ProcessChanSyncMsg(
		ctxb, aliceSyncMsg,
	)
	require.NoError(t, err, "unable to process chan sync msg")
	if len(bobMsgsToSend) != 0 {
		t.Fatalf("expected bob to send %v messages instead "+
			"will send %v: %v", 0, len(bobMsgsToSend),
			spew.Sdump(bobMsgsToSend))
	}

	// When Alice processes Bob's chan sync message, she should realize
	// that she needs to first send a new UpdateFee message, and also a
	// CommitSig.
	aliceMsgsToSend, _, _, err := aliceChannel.ProcessChanSyncMsg(
		ctxb, bobSyncMsg,
	)
	require.NoError(t, err, "unable to process chan sync msg")
	if len(aliceMsgsToSend) != 2 {
		t.Fatalf("expected alice to send %v messages instead "+
			"will send %v: %v", 2, len(aliceMsgsToSend),
			spew.Sdump(aliceMsgsToSend))
	}

	// The first message should be an UpdateFee message.
	retransFeeMsg, ok := aliceMsgsToSend[0].(*lnwire.UpdateFee)
	if !ok {
		t.Fatalf("expected UpdateFee message, instead have: %v",
			spew.Sdump(aliceMsgsToSend[0]))
	}

	// The fee should match exactly the new fee update we applied above.
	if retransFeeMsg.FeePerKw != uint32(newFeeRate) {
		t.Fatalf("fee update doesn't match: expected %v, got %v",
			uint32(newFeeRate), retransFeeMsg)
	}

	// The second, should be a CommitSig message, and be identical to the
	// sig message she sent prior.
	commitSigMsg, ok := aliceMsgsToSend[1].(*lnwire.CommitSig)
	if !ok {
		t.Fatalf("expected a CommitSig message, instead have %v",
			spew.Sdump(aliceMsgsToSend[1]))
	}
	if commitSigMsg.CommitSig != aliceNewCommit.CommitSig {
		t.Fatalf("commit sig msgs don't match: expected %x got %x",
			aliceNewCommit.CommitSig, commitSigMsg.CommitSig)
	}
	if len(commitSigMsg.HtlcSigs) != len(aliceNewCommit.HtlcSigs) {
		t.Fatalf("wrong number of htlc sigs: expected %v, got %v",
			len(aliceNewCommit.HtlcSigs),
			len(commitSigMsg.HtlcSigs))
	}
	for i, htlcSig := range commitSigMsg.HtlcSigs {
		if htlcSig != aliceNewCommit.HtlcSigs[i] {
			t.Fatalf("htlc sig msgs don't match: "+
				"expected %x got %x",
				aliceNewCommit.HtlcSigs[i], htlcSig)
		}
	}

	// Now, we if re-apply the updates to Bob, we should be able to resume
	// the commitment update as normal.
	if err := bobChannel.ReceiveUpdateFee(newFeeRate); err != nil {
		t.Fatalf("unable to update fee for Bob's channel: %v", err)
	}

	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err, "bob unable to process alice's commitment")
	bobRevocation, _, _, err := bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to revoke bob commitment")
	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "bob unable to sign commitment")
	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err, "alice unable to recv revocation")
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err, "alice unable to rev bob's commitment")
	aliceRevocation, _, _, err := aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "alice unable to revoke commitment")
	_, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err, "bob unable to recv revocation")

	// Both parties should now have the latest fee rate locked-in.
	if chainfee.SatPerKWeight(
		aliceChannel.channelState.LocalCommitment.FeePerKw,
	) != newFeeRate {

		t.Fatalf("alice's feePerKw was not locked in")
	}
	if chainfee.SatPerKWeight(
		bobChannel.channelState.LocalCommitment.FeePerKw,
	) != newFeeRate {

		t.Fatalf("bob's feePerKw was not locked in")
	}

	// Finally, we'll add with adding a new HTLC, then forcing a state
	// transition. This should also proceed as normal.
	var bobPreimage [32]byte
	copy(bobPreimage[:], bytes.Repeat([]byte{0xaa}, 32))
	rHash := sha256.Sum256(bobPreimage[:])
	bobHtlc := &lnwire.UpdateAddHTLC{
		PaymentHash: rHash,
		Amount:      lnwire.NewMSatFromSatoshis(20000),
		Expiry:      uint32(10),
	}
	addAndReceiveHTLC(t, bobChannel, aliceChannel, bobHtlc, nil)
	if err := ForceStateTransition(bobChannel, aliceChannel); err != nil {
		t.Fatalf("unable to complete bob's state transition: %v", err)
	}
}

// TestFeeUpdateOldDiskFormat tests that we properly recover FeeUpdates written
// to disk using the old format, where the logIndex was not written.
func TestFeeUpdateOldDiskFormat(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// helper that counts the number of updates, and number of fee updates
	// in the given log.
	countLog := func(log *updateLog) (int, int) {
		var numUpdates, numFee int
		for e := log.Front(); e != nil; e = e.Next() {
			htlc := e.Value
			if htlc.EntryType == FeeUpdate {
				numFee++
			}
			numUpdates++
		}
		return numUpdates, numFee
	}

	// helper that asserts that Alice's local log and Bob's remote log
	// contains the expected number of fee updates and adds.
	assertLogItems := func(expFee, expAdd int) {
		t.Helper()

		expUpd := expFee + expAdd
		upd, fees := countLog(aliceChannel.updateLogs.Local)
		if upd != expUpd {
			t.Fatalf("expected %d updates, found %d in Alice's "+
				"log", expUpd, upd)
		}
		if fees != expFee {
			t.Fatalf("expected %d fee updates, found %d in "+
				"Alice's log", expFee, fees)
		}
		upd, fees = countLog(bobChannel.updateLogs.Remote)
		if upd != expUpd {
			t.Fatalf("expected %d updates, found %d in Bob's log",
				expUpd, upd)
		}
		if fees != expFee {
			t.Fatalf("expected %d fee updates, found %d in Bob's "+
				"log", expFee, fees)
		}
	}

	// First, we'll fetch the current fee rate present within the
	// commitment transactions.
	startingFeeRate := chainfee.SatPerKWeight(
		aliceChannel.channelState.LocalCommitment.FeePerKw,
	)
	newFeeRate := startingFeeRate

	// We will send a few HTLCs and a fee update.
	htlcAmt := lnwire.NewMSatFromSatoshis(0.1 * btcutil.SatoshiPerBitcoin)
	const numHTLCs = 30
	var htlcs []*lnwire.UpdateAddHTLC
	for i := 0; i < numHTLCs; i++ {
		htlc, _ := createHTLC(i, htlcAmt)
		addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)
		htlcs = append(htlcs, htlc)

		if i%5 != 0 {
			continue
		}

		// After every 5th HTLC, we'll also include a fee update.
		newFeeRate += startingFeeRate
		if err := aliceChannel.UpdateFee(newFeeRate); err != nil {
			t.Fatalf("unable to update fee for Alice's channel: %v",
				err)
		}
		if err := bobChannel.ReceiveUpdateFee(newFeeRate); err != nil {
			t.Fatalf("unable to update fee for Bob's channel: %v",
				err)
		}
	}
	// Check that the expected number of items is found in the logs.
	expFee := numHTLCs / 5
	assertLogItems(expFee, numHTLCs)

	// Now, Alice will send a new commitment to Bob, but we'll simulate a
	// connection failure, so Bob doesn't get the signature.
	aliceNewCommitSig, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign commitment")

	// Before restarting Alice, to mimic the old format, we fetch the
	// pending remote commit from disk, set the UpdateFee message's
	// logIndex to 0, and re-write it.
	pendingRemoteCommitDiff, err := aliceChannel.channelState.RemoteCommitChainTip()
	if err != nil {
		t.Fatal(err)
	}
	for i, u := range pendingRemoteCommitDiff.LogUpdates {
		switch u.UpdateMsg.(type) {
		case *lnwire.UpdateFee:
			pendingRemoteCommitDiff.LogUpdates[i].LogIndex = 0
		}
	}
	err = aliceChannel.channelState.AppendRemoteCommitChain(
		pendingRemoteCommitDiff,
	)
	if err != nil {
		t.Fatal(err)
	}

	// Restart both channels to simulate a connection restart. This will
	// trigger a update logs restoration.
	aliceChannel, err = restartChannel(aliceChannel)
	require.NoError(t, err, "unable to restart alice")
	bobChannel, err = restartChannel(bobChannel)
	require.NoError(t, err, "unable to restart channel")

	// After a reconnection, Alice will resend the pending updates, that
	// was not ACKed by Bob, so we re-send the HTLCs and fee updates.
	newFeeRate = startingFeeRate
	for i := 0; i < numHTLCs; i++ {
		htlc := htlcs[i]
		if _, err := bobChannel.ReceiveHTLC(htlc); err != nil {
			t.Fatalf("unable to recv htlc: %v", err)
		}

		if i%5 != 0 {
			continue
		}

		newFeeRate += startingFeeRate
		if err := bobChannel.ReceiveUpdateFee(newFeeRate); err != nil {
			t.Fatalf("unable to update fee for Bob's channel: %v",
				err)
		}
	}
	assertLogItems(expFee, numHTLCs)

	// We send Alice's commitment signatures, and finish the state
	// transition.
	err = bobChannel.ReceiveNewCommitment(aliceNewCommitSig.CommitSigs)
	require.NoError(t, err, "bob unable to process alice's commitment")
	bobRevocation, _, _, err := bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to revoke bob commitment")
	bobNewCommitSigs, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "bob unable to sign commitment")
	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err, "alice unable to recv revocation")
	err = aliceChannel.ReceiveNewCommitment(bobNewCommitSigs.CommitSigs)
	require.NoError(t, err, "alice unable to rev bob's commitment")
	aliceRevocation, _, _, err := aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "alice unable to revoke commitment")
	_, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err, "bob unable to recv revocation")

	// Both parties should now have the latest fee rate locked-in.
	if chainfee.SatPerKWeight(
		aliceChannel.channelState.LocalCommitment.FeePerKw,
	) != newFeeRate {

		t.Fatalf("alice's feePerKw was not locked in")
	}
	if chainfee.SatPerKWeight(
		bobChannel.channelState.LocalCommitment.FeePerKw,
	) != newFeeRate {

		t.Fatalf("bob's feePerKw was not locked in")
	}

	// Finally, to trigger a compactLogs execution, we'll add a new HTLC,
	// then force a state transition.
	htlc, _ := createHTLC(numHTLCs, htlcAmt)
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)
	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("unable to complete bob's state transition: %v", err)
	}

	// Finally, check the logs to make sure all fee updates have been
	// removed...
	assertLogItems(0, numHTLCs+1)

	// ...and the final fee rate locked in.
	if chainfee.SatPerKWeight(
		aliceChannel.channelState.LocalCommitment.FeePerKw,
	) != newFeeRate {

		t.Fatalf("alice's feePerKw was not locked in")
	}
	if chainfee.SatPerKWeight(
		bobChannel.channelState.LocalCommitment.FeePerKw,
	) != newFeeRate {

		t.Fatalf("bob's feePerKw was not locked in")
	}
}

// TestChanSyncUnableToSync tests that if Alice or Bob receive an invalid
// ChannelReestablish messages,then they reject the message and declare the
// channel un-continuable by returning ErrCannotSyncCommitChains.
func TestChanSyncUnableToSync(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// If we immediately send both sides a "bogus" ChanSync message, then
	// they both should conclude that they're unable to synchronize the
	// state.
	badChanSync := &lnwire.ChannelReestablish{
		ChanID: lnwire.NewChanIDFromOutPoint(
			aliceChannel.channelState.FundingOutpoint,
		),
		NextLocalCommitHeight:  1000,
		RemoteCommitTailHeight: 9000,
	}
	_, _, _, err = bobChannel.ProcessChanSyncMsg(ctxb, badChanSync)
	if err != ErrCannotSyncCommitChains {
		t.Fatalf("expected error instead have: %v", err)
	}
	_, _, _, err = aliceChannel.ProcessChanSyncMsg(ctxb, badChanSync)
	if err != ErrCannotSyncCommitChains {
		t.Fatalf("expected error instead have: %v", err)
	}
}

// TestChanSyncInvalidLastSecret ensures that if Alice and Bob have completed
// state transitions in an existing channel, and then send a ChannelReestablish
// message after a restart, the following holds: if Alice has lost data, so she
// sends an invalid commit secret then both parties recognize this as possible
// data loss.
func TestChanSyncInvalidLastSecret(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// We'll create a new instances of Alice before doing any state updates
	// such that we have the initial in memory state at the start of the
	// channel.
	aliceOld, err := restartChannel(aliceChannel)
	if err != nil {
		t.Fatalf("unable to restart alice")
	}

	// First, we'll add an HTLC, and then initiate a state transition
	// between the two parties such that we actually have a prior
	// revocation to send.
	var paymentPreimage [32]byte
	copy(paymentPreimage[:], bytes.Repeat([]byte{1}, 32))
	paymentHash := sha256.Sum256(paymentPreimage[:])
	htlcAmt := lnwire.NewMSatFromSatoshis(btcutil.SatoshiPerBitcoin)
	htlc := &lnwire.UpdateAddHTLC{
		PaymentHash: paymentHash,
		Amount:      htlcAmt,
		Expiry:      uint32(5),
	}
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)

	// Then we'll initiate a state transition to lock in this new HTLC.
	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("unable to complete alice's state transition: %v", err)
	}

	// Next, we'll restart both parties in order to simulate a connection
	// re-establishment.
	aliceChannel, err = restartChannel(aliceChannel)
	require.NoError(t, err, "unable to restart alice")
	bobChannel, err = restartChannel(bobChannel)
	require.NoError(t, err, "unable to restart bob")

	// Next, we'll produce the ChanSync messages for both parties.
	aliceChanSync, err := aliceChannel.channelState.ChanSyncMsg()
	require.NoError(t, err, "unable to generate chan sync msg")
	bobChanSync, err := bobChannel.channelState.ChanSyncMsg()
	require.NoError(t, err, "unable to generate chan sync msg")

	// We'll modify Alice's sync message to have an invalid commitment
	// secret.
	aliceChanSync.LastRemoteCommitSecret[4] ^= 0x01

	// Alice's former self should conclude that she possibly lost data as
	// Bob is sending a valid commit secret for the latest state.
	_, _, _, err = aliceOld.ProcessChanSyncMsg(ctxb, bobChanSync)
	if _, ok := err.(*ErrCommitSyncLocalDataLoss); !ok {
		t.Fatalf("wrong error, expected ErrCommitSyncLocalDataLoss "+
			"instead got: %v", err)
	}

	// Bob should conclude that he should force close the channel, as Alice
	// cannot continue operation.
	_, _, _, err = bobChannel.ProcessChanSyncMsg(ctxb, aliceChanSync)
	if err != ErrInvalidLastCommitSecret {
		t.Fatalf("wrong error, expected ErrInvalidLastCommitSecret, "+
			"instead got: %v", err)
	}
}

// TestChanAvailableBandwidth tests the accuracy of the AvailableBalance()
// method. The value returned from this message should reflect the value
// returned within the commitment state of a channel after the transition is
// initiated.
func TestChanAvailableBandwidth(t *testing.T) {
	t.Parallel()

	cType := channeldb.SingleFunderTweaklessBit

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	aliceReserve := lnwire.NewMSatFromSatoshis(
		aliceChannel.channelState.LocalChanCfg.ChanReserve,
	)
	feeRate := chainfee.SatPerKWeight(
		aliceChannel.channelState.LocalCommitment.FeePerKw,
	)

	assertBandwidthEstimateCorrect := func(aliceInitiate bool,
		numNonDustHtlcsOnCommit lntypes.WeightUnit) {

		// With the HTLC's added, we'll now query the AvailableBalance
		// method for the current available channel bandwidth from
		// Alice's PoV.
		aliceAvailableBalance := aliceChannel.AvailableBalance()

		// With this balance obtained, we'll now trigger a state update
		// to actually determine what the current up to date balance
		// is.
		if aliceInitiate {
			err := ForceStateTransition(aliceChannel, bobChannel)
			if err != nil {
				t.Fatalf("unable to complete alice's state "+
					"transition: %v", err)
			}
		} else {
			err := ForceStateTransition(bobChannel, aliceChannel)
			if err != nil {
				t.Fatalf("unable to complete alice's state "+
					"transition: %v", err)
			}
		}

		// Now, we'll obtain the current available bandwidth in Alice's
		// latest commitment and compare that to the prior estimate.
		aliceState := aliceChannel.State().Snapshot()
		aliceBalance := aliceState.LocalBalance
		commitFee := lnwire.NewMSatFromSatoshis(aliceState.CommitFee)
		commitWeight := CommitWeight(cType)
		commitWeight += numNonDustHtlcsOnCommit * input.HTLCWeight

		// Add weight for an additional htlc because this is also done
		// when evaluating the current balance.
		feeBuffer := CalcFeeBuffer(
			feeRate, commitWeight+input.HTLCWeight,
		)

		// The balance we have available for new HTLCs should be the
		// current local commitment balance, minus the channel reserve
		// and the fee buffer we have to account for.
		expBalance := aliceBalance + commitFee - aliceReserve -
			feeBuffer
		if expBalance != aliceAvailableBalance {
			_, _, line, _ := runtime.Caller(1)
			t.Fatalf("line: %v, incorrect balance: expected %v, "+
				"got %v", line, expBalance, aliceAvailableBalance)
		}
	}

	// First, we'll add 3 outgoing HTLC's from Alice to Bob.
	const numHtlcs = 3
	var dustAmt lnwire.MilliSatoshi = 100000
	alicePreimages := make([][32]byte, numHtlcs)
	for i := 0; i < numHtlcs; i++ {
		htlc, preImage := createHTLC(i, dustAmt)
		addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)

		alicePreimages[i] = preImage
	}

	assertBandwidthEstimateCorrect(true, 0)

	// We'll repeat the same exercise, but with non-dust HTLCs. So we'll
	// crank up the value of the HTLC's we're adding to the commitment
	// transaction.
	htlcAmt := lnwire.NewMSatFromSatoshis(30000)
	for i := 0; i < numHtlcs; i++ {
		htlc, preImage := createHTLC(numHtlcs+i, htlcAmt)
		addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)

		alicePreimages = append(alicePreimages, preImage)
	}

	assertBandwidthEstimateCorrect(true, 3)

	// Next, we'll have Bob settle 5 of Alice's HTLC's, and cancel one of
	// them (in the update log).
	for i := 0; i < (numHtlcs*2)-1; i++ {
		preImage := alicePreimages[i]
		err := bobChannel.SettleHTLC(preImage, uint64(i), nil, nil, nil)
		if err != nil {
			t.Fatalf("unable to settle htlc: %v", err)
		}
		err = aliceChannel.ReceiveHTLCSettle(preImage, uint64(i))
		if err != nil {
			t.Fatalf("unable to settle htlc: %v", err)
		}
	}

	htlcIndex := uint64((numHtlcs * 2) - 1)
	err = bobChannel.FailHTLC(htlcIndex, []byte("f"), nil, nil, nil)
	require.NoError(t, err, "unable to cancel HTLC")
	err = aliceChannel.ReceiveFailHTLC(htlcIndex, []byte("bad"))
	require.NoError(t, err, "unable to recv htlc cancel")

	// We must do a state transition before the balance is available
	// for Alice.
	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("unable to complete alice's state "+
			"transition: %v", err)
	}

	// With the HTLC's settled in the log, we'll now assert that if we
	// initiate a state transition, then our guess was correct.
	assertBandwidthEstimateCorrect(true, 0)

	// TODO(roasbeef): additional tests from diff starting conditions
}

// TestChanAvailableBalanceNearHtlcFee checks that we get the expected reported
// balance when it is close to the fee buffer.
func TestChanAvailableBalanceNearHtlcFee(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	cType := channeldb.SingleFunderTweaklessBit
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, cType,
	)
	require.NoError(t, err, "unable to create test channels")

	// Alice and Bob start with half the channel capacity.
	aliceBalance := lnwire.NewMSatFromSatoshis(5 * btcutil.SatoshiPerBitcoin)
	bobBalance := lnwire.NewMSatFromSatoshis(5 * btcutil.SatoshiPerBitcoin)

	aliceReserve := lnwire.NewMSatFromSatoshis(
		aliceChannel.channelState.LocalChanCfg.ChanReserve,
	)
	bobReserve := lnwire.NewMSatFromSatoshis(
		bobChannel.channelState.LocalChanCfg.ChanReserve,
	)

	aliceDustlimit := lnwire.NewMSatFromSatoshis(
		aliceChannel.channelState.LocalChanCfg.DustLimit,
	)
	feeRate := chainfee.SatPerKWeight(
		aliceChannel.channelState.LocalCommitment.FeePerKw,
	)

	// When calculating the fee buffer sending an htlc we need to account
	// for an additional output on the commitment tx which this send will
	// generate.
	commitWeight := CommitWeight(cType)
	feeBuffer := CalcFeeBuffer(feeRate, commitWeight+input.HTLCWeight)

	htlcFee := lnwire.NewMSatFromSatoshis(
		feeRate.FeeForWeight(input.HTLCWeight),
	)
	commitFee := lnwire.NewMSatFromSatoshis(
		aliceChannel.channelState.LocalCommitment.CommitFee,
	)
	htlcTimeoutFee := lnwire.NewMSatFromSatoshis(
		HtlcTimeoutFee(aliceChannel.channelState.ChanType, feeRate),
	)
	htlcSuccessFee := lnwire.NewMSatFromSatoshis(
		HtlcSuccessFee(aliceChannel.channelState.ChanType, feeRate),
	)

	// Helper method to check the current reported balance.
	checkBalance := func(t *testing.T, expBalanceAlice,
		expBalanceBob lnwire.MilliSatoshi) {

		t.Helper()
		aliceBalance := aliceChannel.AvailableBalance()
		if aliceBalance != expBalanceAlice {
			t.Fatalf("Expected alice balance %v, got %v",
				expBalanceAlice, aliceBalance)
		}

		bobBalance := bobChannel.AvailableBalance()
		if bobBalance != expBalanceBob {
			t.Fatalf("Expected bob balance %v, got %v",
				expBalanceBob, bobBalance)
		}
	}

	// Helper method to send an HTLC from Alice to Bob, decreasing Alice's
	// balance.
	htlcIndex := uint64(0)
	sendHtlc := func(htlcAmt lnwire.MilliSatoshi) {
		t.Helper()

		htlc, preImage := createHTLC(int(htlcIndex), htlcAmt)

		// For this testcase we don't want to enforce the FeeBuffer
		// so that we can verify the edge cases when our balance reaches
		// the channel reserve limit.
		_, err := aliceChannel.addHTLC(htlc, nil, NoBuffer)
		if err != nil {
			t.Fatalf("unable to add htlc: %v", err)
		}
		if _, err := bobChannel.ReceiveHTLC(htlc); err != nil {
			t.Fatalf("unable to recv htlc: %v", err)
		}

		if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
			t.Fatalf("unable to complete alice's state "+
				"transition: %v", err)
		}

		err = bobChannel.SettleHTLC(preImage, htlcIndex, nil, nil, nil)
		if err != nil {
			t.Fatalf("unable to settle htlc: %v", err)
		}
		err = aliceChannel.ReceiveHTLCSettle(preImage, htlcIndex)
		if err != nil {
			t.Fatalf("unable to settle htlc: %v", err)
		}

		if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
			t.Fatalf("unable to complete alice's state "+
				"transition: %v", err)
		}

		htlcIndex++
		aliceBalance -= htlcAmt
		bobBalance += htlcAmt
	}

	// Balance should start out equal to half the channel capacity minus
	// the reserve and the fee buffer because alice is the initiator of
	// the channel.
	expAliceBalance := aliceBalance - aliceReserve - feeBuffer

	// Bob is not the initiator, so he will have all his balance available,
	// since Alice pays for fees. Bob only need to keep his balance above
	// the reserve.
	expBobBalance := bobBalance - bobReserve
	checkBalance(t, expAliceBalance, expBobBalance)

	// Find the minumim size of a non-dust HTLC.
	aliceNonDustHtlc := aliceDustlimit + htlcTimeoutFee

	// Send a HTLC leaving Alice's remaining balance just enough to have
	// nonDustHtlc left after paying the commit fee and htlc fee.
	htlcAmt := aliceBalance - (aliceReserve + feeBuffer + aliceNonDustHtlc)
	sendHtlc(htlcAmt)

	// Now the real balance left will be
	// nonDustHtlc+commitfee+aliceReserve+htlcfee. The available balance
	// reported will just be nonDustHtlc, since the rest of the balance is
	// reserved.
	expAliceBalance = aliceNonDustHtlc
	expBobBalance = bobBalance - bobReserve
	checkBalance(t, expAliceBalance, expBobBalance)

	// Send an dust HTLC using all but one msat of the reported balance.
	htlcAmt = aliceNonDustHtlc - 1
	sendHtlc(htlcAmt)

	// 1 msat should be left.
	expAliceBalance = 1

	// Bob should still have all his balance available, since even though
	// Alice cannot afford to add a non-dust HTLC, she can afford to add a
	// non-dust HTLC from Bob.
	expBobBalance = bobBalance - bobReserve
	checkBalance(t, expAliceBalance, expBobBalance)

	// Sendng the last msat.
	htlcAmt = 1
	sendHtlc(htlcAmt)

	// No balance left.
	expAliceBalance = 0

	// We try to always reserve enough for the non-iniitator to be able to
	// add an HTLC, hence Bob should still have all his non-reserved
	// balance available.
	expBobBalance = bobBalance - bobReserve
	checkBalance(t, expAliceBalance, expBobBalance)

	// The available balance is zero for alice but there is still the
	// fee buffer left (which includes the current commitment weight).
	// We send the buffer to bob but also keep the funds for the htlc
	// available otherwise we would not able to send this amount.
	htlcAmt = feeBuffer - commitFee - htlcFee
	sendHtlc(htlcAmt)

	// Now we send a dust htlc of 1 msat to bob so that we cannot afford
	// to put another non-dust htlc on this commitment.
	htlcAmt = 1
	sendHtlc(htlcAmt)

	// Now Alice balance is so low that she cannot even afford to add a new
	// HTLC from Bob to the commitment transaction. Bob's balance should
	// reflect this, by only reporting dust amount being available. Alice
	// should still report a zero balance.

	// Since the dustlimit is different for the two commitments, the
	// largest HTLC Bob can send that Alice can afford on both commitments
	// (remember she cannot afford to pay the HTLC fee) is the largest dust
	// HTLC on Alice's commitemnt, since her dust limit is lower.
	bobNonDustHtlc := aliceDustlimit + htlcSuccessFee
	expBobBalance = bobNonDustHtlc - 1
	expAliceBalance = 0
	checkBalance(t, expAliceBalance, expBobBalance)
}

// TestChanCommitWeightDustHtlcs checks that we correctly calculate the
// commitment weight when some HTLCs are dust.
func TestChanCommitWeightDustHtlcs(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	aliceDustlimit := lnwire.NewMSatFromSatoshis(
		aliceChannel.channelState.LocalChanCfg.DustLimit,
	)
	bobDustlimit := lnwire.NewMSatFromSatoshis(
		bobChannel.channelState.LocalChanCfg.DustLimit,
	)

	feeRate := chainfee.SatPerKWeight(
		aliceChannel.channelState.LocalCommitment.FeePerKw,
	)
	htlcTimeoutFee := lnwire.NewMSatFromSatoshis(
		HtlcTimeoutFee(aliceChannel.channelState.ChanType, feeRate),
	)
	htlcSuccessFee := lnwire.NewMSatFromSatoshis(
		HtlcSuccessFee(aliceChannel.channelState.ChanType, feeRate),
	)

	// Helper method to add an HTLC from Alice to Bob.
	htlcIndex := uint64(0)
	addHtlc := func(htlcAmt lnwire.MilliSatoshi) lntypes.Preimage {
		t.Helper()

		htlc, preImage := createHTLC(int(htlcIndex), htlcAmt)
		addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)
		if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
			t.Fatalf("unable to complete alice's state "+
				"transition: %v", err)
		}

		return preImage
	}

	settleHtlc := func(preImage lntypes.Preimage) {
		t.Helper()

		err = bobChannel.SettleHTLC(preImage, htlcIndex, nil, nil, nil)
		if err != nil {
			t.Fatalf("unable to settle htlc: %v", err)
		}
		err = aliceChannel.ReceiveHTLCSettle(preImage, htlcIndex)
		if err != nil {
			t.Fatalf("unable to settle htlc: %v", err)
		}

		if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
			t.Fatalf("unable to complete alice's state "+
				"transition: %v", err)
		}
		htlcIndex++
	}

	// Helper method that fetches the current remote commitment weight
	// fromt the given channel's POV.
	// When sending htlcs we enforce the feebuffer on the commitment
	// transaction.
	remoteCommitWeight := func(lc *LightningChannel) lntypes.WeightUnit {
		remoteACKedIndex :=
			lc.commitChains.Local.tip().messageIndices.Remote

		htlcView := lc.fetchHTLCView(remoteACKedIndex,
			lc.updateLogs.Local.logIndex)

		_, w := lc.availableCommitmentBalance(
			htlcView, lntypes.Remote, FeeBuffer,
		)

		return w
	}

	// Start by getting the initial remote commitment weight seen from
	// Alice's perspective. At this point there are no HTLCs on the
	// commitment.
	weight1 := remoteCommitWeight(aliceChannel)

	// Now add an HTLC that will be just below Bob's dustlimit.
	// Since this is an HTLC added from Alice on Bob's commitment, we will
	// use the HTLC success fee.
	bobDustHtlc := bobDustlimit + htlcSuccessFee - 1
	preimg := addHtlc(bobDustHtlc)

	// Now get the current weight of the remote commitment. We expect it to
	// not have changed, since the HTLC we added is considered dust.
	weight2 := remoteCommitWeight(aliceChannel)
	require.Equal(t, weight1, weight2)

	// In addition, we expect this weight to result in the fee we currently
	// see being paid on the remote commitent.
	calcFee := feeRate.FeeForWeight(weight2)
	remoteCommitFee := aliceChannel.channelState.RemoteCommitment.CommitFee
	require.Equal(t, calcFee, remoteCommitFee)

	// Settle the HTLC, bringing commitment weight back to base.
	settleHtlc(preimg)

	// Now we do a similar check from Bob's POV. Start with getting his
	// current view of Alice's commitment weight.
	weight1 = remoteCommitWeight(bobChannel)

	// We'll add an HTLC from Alice to Bob, that is just above dust on
	// Alice's commitment. Now we'll use the timeout fee.
	aliceDustHtlc := aliceDustlimit + htlcTimeoutFee
	preimg = addHtlc(aliceDustHtlc)

	// Get the current remote commitment weight from Bob's POV, and ensure
	// it is now heavier, since Alice added a non-dust HTLC.
	weight2 = remoteCommitWeight(bobChannel)
	require.Greater(t, weight2, weight1)

	// Ensure the current remote commit has the expected commitfee.
	calcFee = feeRate.FeeForWeight(weight2)
	remoteCommitFee = bobChannel.channelState.RemoteCommitment.CommitFee
	require.Equal(t, calcFee, remoteCommitFee)

	settleHtlc(preimg)
}

// TestSignCommitmentFailNotLockedIn tests that a channel will not attempt to
// create a new state if it doesn't yet know of the next revocation point for
// the remote party.
func TestSignCommitmentFailNotLockedIn(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, _, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// Next, we'll modify Alice's internal state to omit knowledge of Bob's
	// next revocation point.
	aliceChannel.channelState.RemoteNextRevocation = nil

	// If we now try to initiate a state update, then it should fail as
	// Alice is unable to actually create a new state.
	_, err = aliceChannel.SignNextCommitment(ctxb)
	if err != ErrNoWindow {
		t.Fatalf("expected ErrNoWindow, instead have: %v", err)
	}
}

// TestLockedInHtlcForwardingSkipAfterRestart ensures that after a restart, a
// state machine doesn't attempt to re-forward any HTLC's that were already
// locked in, but in a prior state.
func TestLockedInHtlcForwardingSkipAfterRestart(t *testing.T) {
	t.Parallel()

	// First, we'll make a channel between Alice and Bob.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// We'll now add two HTLC's from Alice to Bob, then Alice will initiate
	// a state transition.
	var htlcAmt lnwire.MilliSatoshi = 100000
	htlc, _ := createHTLC(0, htlcAmt)
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)

	htlc2, _ := createHTLC(1, htlcAmt)
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc2, nil)

	// We'll now manually initiate a state transition between Alice and
	// bob.
	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	if err != nil {
		t.Fatal(err)
	}
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	if err != nil {
		t.Fatal(err)
	}
	bobRevocation, _, _, err := bobChannel.RevokeCurrentCommitment()
	if err != nil {
		t.Fatal(err)
	}

	// Alice should detect that she doesn't need to forward any HTLC's.
	fwdPkg, _, err := aliceChannel.ReceiveRevocation(bobRevocation)
	if err != nil {
		t.Fatal(err)
	}
	if len(fwdPkg.Adds) != 0 {
		t.Fatalf("alice shouldn't forward any HTLC's, instead wants to "+
			"forward %v htlcs", len(fwdPkg.Adds))
	}
	if len(fwdPkg.SettleFails) != 0 {
		t.Fatalf("alice shouldn't forward any HTLC's, instead wants to "+
			"forward %v htlcs", len(fwdPkg.SettleFails))
	}

	// Now, have Bob initiate a transition to lock in the Adds sent by
	// Alice.
	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	if err != nil {
		t.Fatal(err)
	}

	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	if err != nil {
		t.Fatal(err)
	}
	aliceRevocation, _, _, err := aliceChannel.RevokeCurrentCommitment()
	if err != nil {
		t.Fatal(err)
	}

	// Bob should now detect that he now has 2 incoming HTLC's that he can
	// forward along.
	fwdPkg, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	if err != nil {
		t.Fatal(err)
	}
	if len(fwdPkg.Adds) != 2 {
		t.Fatalf("bob should forward 2 hltcs, instead has %v",
			len(fwdPkg.Adds))
	}
	if len(fwdPkg.SettleFails) != 0 {
		t.Fatalf("bob should forward 0 hltcs, instead has %v",
			len(fwdPkg.SettleFails))
	}

	// We'll now restart both Alice and Bob. This emulates a reconnection
	// between the two peers.
	aliceChannel, err = restartChannel(aliceChannel)
	require.NoError(t, err, "unable to restart alice")
	bobChannel, err = restartChannel(bobChannel)
	require.NoError(t, err, "unable to restart bob")

	// With both nodes restarted, Bob will now attempt to cancel one of
	// Alice's HTLC's.
	err = bobChannel.FailHTLC(htlc.ID, []byte("failreason"), nil, nil, nil)
	require.NoError(t, err, "unable to cancel HTLC")
	err = aliceChannel.ReceiveFailHTLC(htlc.ID, []byte("bad"))
	require.NoError(t, err, "unable to recv htlc cancel")

	// We'll now initiate another state transition, but this time Bob will
	// lead.
	bobNewCommit, err = bobChannel.SignNextCommitment(ctxb)
	if err != nil {
		t.Fatal(err)
	}
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	if err != nil {
		t.Fatal(err)
	}
	aliceRevocation, _, _, err = aliceChannel.RevokeCurrentCommitment()
	if err != nil {
		t.Fatal(err)
	}

	// At this point, Bob receives the revocation from Alice, which is now
	// his signal to examine all the HTLC's that have been locked in to
	// process.
	fwdPkg, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	if err != nil {
		t.Fatal(err)
	}

	// Bob should detect that he doesn't need to forward *any* HTLC's, as
	// he was the one that initiated extending the commitment chain of
	// Alice.
	if len(fwdPkg.Adds) != 0 {
		t.Fatalf("alice shouldn't forward any HTLC's, instead wants to "+
			"forward %v htlcs", len(fwdPkg.Adds))
	}
	if len(fwdPkg.SettleFails) != 0 {
		t.Fatalf("alice shouldn't forward any HTLC's, instead wants to "+
			"forward %v htlcs", len(fwdPkg.SettleFails))
	}

	// Now, begin another state transition led by Alice, and fail the second
	// HTLC part-way through the dance.
	aliceNewCommit, err = aliceChannel.SignNextCommitment(ctxb)
	if err != nil {
		t.Fatal(err)
	}
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	if err != nil {
		t.Fatal(err)
	}

	// Failing the HTLC here will cause the update to be included in Alice's
	// remote log, but it should not be committed by this transition.
	err = bobChannel.FailHTLC(htlc2.ID, []byte("failreason"), nil, nil, nil)
	require.NoError(t, err, "unable to cancel HTLC")
	err = aliceChannel.ReceiveFailHTLC(htlc2.ID, []byte("bad"))
	require.NoError(t, err, "unable to recv htlc cancel")

	bobRevocation, _, finalHtlcs, err := bobChannel.
		RevokeCurrentCommitment()
	if err != nil {
		t.Fatal(err)
	}

	// Check finalHtlcs for the expected final resolution.
	require.Len(t, finalHtlcs, 1, "final htlc expected")
	for _, settled := range finalHtlcs {
		require.False(t, settled, "final fail expected")
	}

	// Alice should detect that she doesn't need to forward any Adds's, but
	// that the Fail has been locked in an can be forwarded.
	fwdPkg, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	if err != nil {
		t.Fatal(err)
	}

	adds := fwdPkg.Adds
	settleFails := fwdPkg.SettleFails
	if len(adds) != 0 {
		t.Fatalf("alice shouldn't forward any HTLC's, instead wants to "+
			"forward %v htlcs", len(fwdPkg.Adds))
	}
	if len(settleFails) != 1 {
		t.Fatalf("alice should only forward %d HTLC's, instead wants to "+
			"forward %v htlcs", 1, len(fwdPkg.SettleFails))
	}

	fail, ok := settleFails[0].UpdateMsg.(*lnwire.UpdateFailHTLC)
	if !ok {
		t.Fatalf("expected UpdateFailHTLC, got %T",
			settleFails[0].UpdateMsg)
	}
	if fail.ID != htlc.ID {
		t.Fatalf("alice should forward fail for htlcid=%d, instead "+
			"forwarding id=%d", htlc.ID,
			fail.ID)
	}

	// We'll now restart both Alice and Bob. This emulates a reconnection
	// between the two peers.
	aliceChannel, err = restartChannel(aliceChannel)
	require.NoError(t, err, "unable to restart alice")
	bobChannel, err = restartChannel(bobChannel)
	require.NoError(t, err, "unable to restart bob")

	// Re-add the Fail to both Alice and Bob's channels, as the non-committed
	// update will not have survived the restart.
	err = bobChannel.FailHTLC(htlc2.ID, []byte("failreason"), nil, nil, nil)
	require.NoError(t, err, "unable to cancel HTLC")
	err = aliceChannel.ReceiveFailHTLC(htlc2.ID, []byte("bad"))
	require.NoError(t, err, "unable to recv htlc cancel")

	// Have Alice initiate a state transition, which does not include the
	// HTLCs just re-added to the channel state.
	aliceNewCommit, err = aliceChannel.SignNextCommitment(ctxb)
	if err != nil {
		t.Fatal(err)
	}
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	if err != nil {
		t.Fatal(err)
	}
	bobRevocation, _, _, err = bobChannel.RevokeCurrentCommitment()
	if err != nil {
		t.Fatal(err)
	}

	// Alice should detect that she doesn't need to forward any HTLC's, as
	// the updates haven't been committed by Bob yet.
	fwdPkg, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	if err != nil {
		t.Fatal(err)
	}
	if len(fwdPkg.Adds) != 0 {
		t.Fatalf("alice shouldn't forward any HTLC's, instead wants to "+
			"forward %v htlcs", len(fwdPkg.Adds))
	}
	if len(fwdPkg.SettleFails) != 0 {
		t.Fatalf("alice shouldn't forward any HTLC's, instead wants to "+
			"forward %v htlcs", len(fwdPkg.SettleFails))
	}

	// Now initiate a final update from Bob to lock in the final Fail.
	bobNewCommit, err = bobChannel.SignNextCommitment(ctxb)
	if err != nil {
		t.Fatal(err)
	}

	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	if err != nil {
		t.Fatal(err)
	}

	aliceRevocation, _, _, err = aliceChannel.RevokeCurrentCommitment()
	if err != nil {
		t.Fatal(err)
	}

	// Bob should detect that he has nothing to forward, as he hasn't
	// received any HTLCs.
	fwdPkg, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	if err != nil {
		t.Fatal(err)
	}
	if len(fwdPkg.Adds) != 0 {
		t.Fatalf("bob should forward 4 hltcs, instead has %v",
			len(fwdPkg.Adds))
	}
	if len(fwdPkg.SettleFails) != 0 {
		t.Fatalf("bob should forward 0 hltcs, instead has %v",
			len(fwdPkg.SettleFails))
	}

	// Finally, have Bob initiate a state transition that locks in the Fail
	// added after the restart.
	aliceNewCommit, err = aliceChannel.SignNextCommitment(ctxb)
	if err != nil {
		t.Fatal(err)
	}
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	if err != nil {
		t.Fatal(err)
	}
	bobRevocation, _, _, err = bobChannel.RevokeCurrentCommitment()
	if err != nil {
		t.Fatal(err)
	}

	// When Alice receives the revocation, she should detect that she
	// can now forward the freshly locked-in Fail.
	fwdPkg, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	if err != nil {
		t.Fatal(err)
	}

	adds = fwdPkg.Adds
	settleFails = fwdPkg.SettleFails
	if len(adds) != 0 {
		t.Fatalf("alice shouldn't forward any HTLC's, instead wants to "+
			"forward %v htlcs", len(adds))
	}
	if len(settleFails) != 1 {
		t.Fatalf("alice should only forward one HTLC, instead wants to "+
			"forward %v htlcs", len(settleFails))
	}

	fail, ok = settleFails[0].UpdateMsg.(*lnwire.UpdateFailHTLC)
	if !ok {
		t.Fatalf("expected UpdateFailHTLC, got %T",
			settleFails[0].UpdateMsg)
	}
	if fail.ID != htlc2.ID {
		t.Fatalf("alice should forward fail for htlcid=%d, instead "+
			"forwarding id=%d", htlc2.ID,
			fail.ID)
	}
}

// TestInvalidCommitSigError tests that if the remote party sends us an invalid
// commitment signature, then we'll reject it and return a special error that
// contains information to allow the remote party to debug their issues.
func TestInvalidCommitSigError(t *testing.T) {
	t.Parallel()

	// First, we'll make a channel between Alice and Bob.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// With the channel established, we'll now send a single HTLC from
	// Alice to Bob.
	var htlcAmt lnwire.MilliSatoshi = 100000
	htlc, _ := createHTLC(0, htlcAmt)
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)

	// Alice will now attempt to initiate a state transition.
	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign new commit")

	// Before the signature gets to Bob, we'll mutate it, such that the
	// signature is now actually invalid.
	aliceSigCopy := aliceNewCommit.CommitSig.Copy()
	aliceSigCopyBytes := aliceSigCopy.RawBytes()
	aliceSigCopyBytes[0] ^= 80
	aliceNewCommit.CommitSig, err = lnwire.NewSigFromWireECDSA(
		aliceSigCopyBytes,
	)
	require.NoError(t, err)

	// Bob should reject this new state, and return the proper error.
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	if err == nil {
		t.Fatalf("bob accepted invalid state but shouldn't have")
	}
	if _, ok := err.(*InvalidCommitSigError); !ok {
		t.Fatalf("bob sent incorrect error, expected %T, got %T",
			&InvalidCommitSigError{}, err)
	}
}

// TestChannelUnilateralCloseHtlcResolution tests that in the case of a
// unilateral channel closure, then the party that didn't broadcast the
// commitment is able to properly sweep all relevant outputs.
func TestChannelUnilateralCloseHtlcResolution(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// We'll start off the test by adding an HTLC in both directions, then
	// initiating enough state transitions to lock both of them in.
	htlcAmount := lnwire.NewMSatFromSatoshis(20000)
	htlcAlice, _ := createHTLC(0, htlcAmount)
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlcAlice, nil)
	htlcBob, preimageBob := createHTLC(0, htlcAmount)
	addAndReceiveHTLC(t, bobChannel, aliceChannel, htlcBob, nil)
	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("Can't update the channel state: %v", err)
	}
	if err := ForceStateTransition(bobChannel, aliceChannel); err != nil {
		t.Fatalf("Can't update the channel state: %v", err)
	}

	// With both HTLC's locked in, we'll now simulate Bob force closing the
	// transaction on Alice.
	bobForceClose, err := bobChannel.ForceClose()
	require.NoError(t, err, "unable to close")

	// We'll then use Bob's transaction to trigger a spend notification for
	// Alice.
	closeTx := bobForceClose.CloseTx
	commitTxHash := closeTx.TxHash()
	spendDetail := &chainntnfs.SpendDetail{
		SpendingTx:    closeTx,
		SpenderTxHash: &commitTxHash,
	}
	aliceCloseSummary, err := NewUnilateralCloseSummary(
		aliceChannel.channelState, aliceChannel.Signer,
		spendDetail,
		aliceChannel.channelState.RemoteCommitment,
		aliceChannel.channelState.RemoteCurrentRevocation,
		fn.Some[AuxLeafStore](&MockAuxLeafStore{}),
		fn.Some[AuxContractResolver](&MockAuxContractResolver{}),
	)
	require.NoError(t, err, "unable to create alice close summary")

	// She should detect that she can sweep both the outgoing HTLC as well
	// as the incoming one from Bob.
	if len(aliceCloseSummary.HtlcResolutions.OutgoingHTLCs) != 1 {
		t.Fatalf("alice out htlc resolutions not populated: expected %v "+
			"htlcs, got %v htlcs",
			1, len(aliceCloseSummary.HtlcResolutions.OutgoingHTLCs))
	}
	if len(aliceCloseSummary.HtlcResolutions.IncomingHTLCs) != 1 {
		t.Fatalf("alice in htlc resolutions not populated: expected %v "+
			"htlcs, got %v htlcs",
			1, len(aliceCloseSummary.HtlcResolutions.IncomingHTLCs))
	}

	outHtlcResolution := aliceCloseSummary.HtlcResolutions.OutgoingHTLCs[0]
	inHtlcResolution := aliceCloseSummary.HtlcResolutions.IncomingHTLCs[0]

	// First, we'll ensure that Alice can directly spend the outgoing HTLC
	// given a transaction with the proper lock time set.
	receiverHtlcScript := closeTx.TxOut[outHtlcResolution.ClaimOutpoint.Index].PkScript
	sweepTx := wire.NewMsgTx(2)
	sweepTx.AddTxIn(&wire.TxIn{
		PreviousOutPoint: outHtlcResolution.ClaimOutpoint,
	})
	sweepTx.AddTxOut(&wire.TxOut{
		PkScript: receiverHtlcScript,
		Value:    outHtlcResolution.SweepSignDesc.Output.Value,
	})
	outHtlcResolution.SweepSignDesc.InputIndex = 0
	outHtlcResolution.SweepSignDesc.SigHashes = input.NewTxSigHashesV0Only(
		sweepTx,
	)
	sweepTx.LockTime = outHtlcResolution.Expiry

	// With the transaction constructed, we'll generate a witness that
	// should be valid for it, and verify using an instance of Script.
	sweepTx.TxIn[0].Witness, err = input.ReceiverHtlcSpendTimeout(
		aliceChannel.Signer, &outHtlcResolution.SweepSignDesc,
		sweepTx, int32(outHtlcResolution.Expiry),
	)
	require.NoError(t, err, "unable to witness")
	vm, err := txscript.NewEngine(
		outHtlcResolution.SweepSignDesc.Output.PkScript,
		sweepTx, 0, txscript.StandardVerifyFlags, nil,
		nil, outHtlcResolution.SweepSignDesc.Output.Value,
		txscript.NewCannedPrevOutputFetcher(
			outHtlcResolution.SweepSignDesc.Output.PkScript,
			outHtlcResolution.SweepSignDesc.Output.Value,
		),
	)
	require.NoError(t, err, "unable to create engine")
	if err := vm.Execute(); err != nil {
		t.Fatalf("htlc timeout spend is invalid: %v", err)
	}

	// Next, we'll ensure that we're able to sweep the incoming HTLC with a
	// similar sweep transaction, this time using the payment pre-image.
	senderHtlcScript := closeTx.TxOut[inHtlcResolution.ClaimOutpoint.Index].PkScript
	sweepTx = wire.NewMsgTx(2)
	sweepTx.AddTxIn(&wire.TxIn{
		PreviousOutPoint: inHtlcResolution.ClaimOutpoint,
	})
	sweepTx.AddTxOut(&wire.TxOut{
		PkScript: senderHtlcScript,
		Value:    inHtlcResolution.SweepSignDesc.Output.Value,
	})
	inHtlcResolution.SweepSignDesc.InputIndex = 0
	inHtlcResolution.SweepSignDesc.SigHashes = input.NewTxSigHashesV0Only(
		sweepTx,
	)
	sweepTx.TxIn[0].Witness, err = input.SenderHtlcSpendRedeem(
		aliceChannel.Signer, &inHtlcResolution.SweepSignDesc,
		sweepTx, preimageBob[:],
	)
	if err != nil {
		t.Fatalf("unable to generate witness for success "+
			"output: %v", err)
	}

	// Finally, we'll verify the constructed witness to ensure that Alice
	// can properly sweep the output.
	vm, err = txscript.NewEngine(
		inHtlcResolution.SweepSignDesc.Output.PkScript,
		sweepTx, 0, txscript.StandardVerifyFlags, nil,
		nil, inHtlcResolution.SweepSignDesc.Output.Value,
		txscript.NewCannedPrevOutputFetcher(
			inHtlcResolution.SweepSignDesc.Output.PkScript,
			inHtlcResolution.SweepSignDesc.Output.Value,
		),
	)
	require.NoError(t, err, "unable to create engine")
	if err := vm.Execute(); err != nil {
		t.Fatalf("htlc timeout spend is invalid: %v", err)
	}
}

// TestChannelUnilateralClosePendingCommit tests that if the remote party
// broadcasts their pending commit (hasn't yet revoked the lower one), then
// we'll create a proper unilateral channel clsoure that can sweep the created
// outputs.
func TestChannelUnilateralClosePendingCommit(t *testing.T) {
	t.Parallel()

	// Create a test channel which will be used for the duration of this
	// unittest. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// First, we'll add an HTLC from Alice to Bob, just to be be able to
	// create a new state transition.
	htlcAmount := lnwire.NewMSatFromSatoshis(20000)
	htlcAlice, _ := createHTLC(0, htlcAmount)
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlcAlice, nil)

	// With the HTLC added, we'll now manually initiate a state transition
	// from Alice to Bob.
	_, err = aliceChannel.SignNextCommitment(ctxb)
	if err != nil {
		t.Fatal(err)
	}

	// At this point, Alice's commitment chain should have a new pending
	// commit for Bob. We'll extract it so we can simulate Bob broadcasting
	// the commitment due to an issue.
	bobCommit := aliceChannel.commitChains.Remote.tip().txn
	bobTxHash := bobCommit.TxHash()
	spendDetail := &chainntnfs.SpendDetail{
		SpenderTxHash: &bobTxHash,
		SpendingTx:    bobCommit,
	}

	// At this point, if we attempt to create a unilateral close summary
	// using this commitment, but with the wrong state, we should find that
	// our output wasn't picked up.
	aliceWrongCloseSummary, err := NewUnilateralCloseSummary(
		aliceChannel.channelState, aliceChannel.Signer,
		spendDetail,
		aliceChannel.channelState.RemoteCommitment,
		aliceChannel.channelState.RemoteCurrentRevocation,
		fn.Some[AuxLeafStore](&MockAuxLeafStore{}),
		fn.Some[AuxContractResolver](&MockAuxContractResolver{}),
	)
	require.NoError(t, err, "unable to create alice close summary")

	if aliceWrongCloseSummary.CommitResolution != nil {
		t.Fatalf("alice shouldn't have found self output")
	}

	// If we create the close summary again, but this time use Alice's
	// pending commit to Bob, then the unilateral close summary should be
	// properly populated.
	aliceRemoteChainTip, err := aliceChannel.channelState.RemoteCommitChainTip()
	require.NoError(t, err, "unable to fetch remote chain tip")
	aliceCloseSummary, err := NewUnilateralCloseSummary(
		aliceChannel.channelState, aliceChannel.Signer,
		spendDetail,
		aliceRemoteChainTip.Commitment,
		aliceChannel.channelState.RemoteNextRevocation,
		fn.Some[AuxLeafStore](&MockAuxLeafStore{}),
		fn.Some[AuxContractResolver](&MockAuxContractResolver{}),
	)
	require.NoError(t, err, "unable to create alice close summary")

	// With this proper version, Alice's commit resolution should have been
	// properly located.
	if aliceCloseSummary.CommitResolution == nil {
		t.Fatalf("unable to find alice's commit resolution")
	}

	// The proper short channel ID should also be set in Alice's close
	// channel summary.
	if aliceCloseSummary.ChannelCloseSummary.ShortChanID !=
		aliceChannel.ShortChanID() {

		t.Fatalf("wrong short chan ID, expected %v got %v",
			aliceChannel.ShortChanID(),
			aliceCloseSummary.ChannelCloseSummary.ShortChanID)
	}

	aliceSignDesc := aliceCloseSummary.CommitResolution.SelfOutputSignDesc

	// Finally, we'll ensure that we're able to properly sweep our output
	// from using the materials within the unilateral close summary.
	sweepTx := wire.NewMsgTx(2)
	sweepTx.AddTxIn(&wire.TxIn{
		PreviousOutPoint: aliceCloseSummary.CommitResolution.SelfOutPoint,
	})
	sweepTx.AddTxOut(&wire.TxOut{
		PkScript: testHdSeed[:],
		Value:    aliceSignDesc.Output.Value,
	})
	aliceSignDesc.SigHashes = input.NewTxSigHashesV0Only(sweepTx)
	sweepTx.TxIn[0].Witness, err = input.CommitSpendNoDelay(
		aliceChannel.Signer, &aliceSignDesc, sweepTx, false,
	)
	require.NoError(t, err, "unable to generate sweep witness")

	// If we validate the signature on the new sweep transaction, it should
	// be fully valid.
	vm, err := txscript.NewEngine(
		aliceSignDesc.Output.PkScript, sweepTx, 0,
		txscript.StandardVerifyFlags, nil, nil,
		aliceSignDesc.Output.Value,
		txscript.NewCannedPrevOutputFetcher(
			aliceSignDesc.Output.PkScript,
			aliceSignDesc.Output.Value,
		),
	)
	require.NoError(t, err, "unable to create engine")
	if err := vm.Execute(); err != nil {
		t.Fatalf("htlc timeout spend is invalid: %v", err)
	}
}

// TestDesyncHTLCs checks that we cannot add HTLCs that would make the
// balance negative, when the remote and local update logs are desynced.
func TestDesyncHTLCs(t *testing.T) {
	t.Parallel()

	// We'll kick off the test by creating our channels which both are
	// loaded with 5 BTC each.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// First add one HTLC of value 4.1 BTC.
	htlcAmt := lnwire.NewMSatFromSatoshis(4.1 * btcutil.SatoshiPerBitcoin)
	htlc, _ := createHTLC(0, htlcAmt)
	aliceIndex, err := aliceChannel.AddHTLC(htlc, nil)
	require.NoError(t, err, "unable to add htlc")
	bobIndex, err := bobChannel.ReceiveHTLC(htlc)
	require.NoError(t, err, "unable to recv htlc")

	// Lock this HTLC in.
	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("unable to complete state update: %v", err)
	}

	// Now let Bob fail this HTLC.
	err = bobChannel.FailHTLC(bobIndex, []byte("failreason"), nil, nil, nil)
	require.NoError(t, err, "unable to cancel HTLC")
	if err := aliceChannel.ReceiveFailHTLC(aliceIndex, []byte("bad")); err != nil {
		t.Fatalf("unable to recv htlc cancel: %v", err)
	}

	// Alice now has gotten all her original balance (5 BTC) back, however,
	// adding a new HTLC at this point SHOULD fail, since if she adds the
	// HTLC and signs the next state, Bob cannot assume she received the
	// FailHTLC, and must assume she doesn't have the necessary balance
	// available.
	//
	// We try adding an HTLC of value 1 BTC, which should fail because the
	// balance is unavailable.
	htlcAmt = lnwire.NewMSatFromSatoshis(1 * btcutil.SatoshiPerBitcoin)
	htlc, _ = createHTLC(1, htlcAmt)
	_, err = aliceChannel.AddHTLC(htlc, nil)
	require.ErrorIs(t, err, ErrBelowChanReserve)

	// Now do a state transition, which will ACK the FailHTLC, making Alice
	// able to add the new HTLC.
	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("unable to complete state update: %v", err)
	}
	if _, err = aliceChannel.AddHTLC(htlc, nil); err != nil {
		t.Fatalf("unable to add htlc: %v", err)
	}
}

// TODO(roasbeef): testing.Quick test case for retrans!!!

// TestMaxAcceptedHTLCs tests that the correct error message (ErrMaxHTLCNumber)
// is thrown when a node tries to accept more than MaxAcceptedHTLCs in a
// channel.
func TestMaxAcceptedHTLCs(t *testing.T) {
	t.Parallel()

	// We'll kick off the test by creating our channels which both are
	// loaded with 5 BTC each.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// One over the maximum number of HTLCs that either can accept.
	const numHTLCs = 12

	// Set the remote's required MaxAcceptedHtlcs. This means that Alice
	// can only offer the remote up to numHTLCs HTLCs.
	aliceChannel.channelState.LocalChanCfg.MaxAcceptedHtlcs = numHTLCs
	bobChannel.channelState.RemoteChanCfg.MaxAcceptedHtlcs = numHTLCs

	// Similarly, set the remote config's MaxAcceptedHtlcs. This means
	// that the remote will be aware that Bob will only accept up to
	// numHTLCs at a time.
	aliceChannel.channelState.RemoteChanCfg.MaxAcceptedHtlcs = numHTLCs
	bobChannel.channelState.LocalChanCfg.MaxAcceptedHtlcs = numHTLCs

	// Each HTLC amount is 0.1 BTC.
	htlcAmt := lnwire.NewMSatFromSatoshis(0.1 * btcutil.SatoshiPerBitcoin)

	// htlcID is used to keep track of the HTLC that Bob will fail back to
	// Alice.
	var htlcID uint64

	// Send the maximum allowed number of HTLCs.
	for i := 0; i < numHTLCs; i++ {
		htlc, _ := createHTLC(i, htlcAmt)
		addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)

		// Just assign htlcID to the last received HTLC.
		htlcID = htlc.ID
	}

	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("unable to transition state: %v", err)
	}

	// The next HTLC should fail with ErrMaxHTLCNumber.
	htlc, _ := createHTLC(numHTLCs, htlcAmt)
	_, err = aliceChannel.AddHTLC(htlc, nil)
	if err != ErrMaxHTLCNumber {
		t.Fatalf("expected ErrMaxHTLCNumber, instead received: %v", err)
	}

	// Receiving the next HTLC should fail.
	if _, err := bobChannel.ReceiveHTLC(htlc); err != ErrMaxHTLCNumber {
		t.Fatalf("expected ErrMaxHTLCNumber, instead received: %v", err)
	}

	// Bob will fail the htlc specified by htlcID and then force a state
	// transition.
	err = bobChannel.FailHTLC(htlcID, []byte{}, nil, nil, nil)
	require.NoError(t, err, "unable to fail htlc")

	if err := aliceChannel.ReceiveFailHTLC(htlcID, []byte{}); err != nil {
		t.Fatalf("unable to receive fail htlc: %v", err)
	}

	if err := ForceStateTransition(bobChannel, aliceChannel); err != nil {
		t.Fatalf("unable to transition state: %v", err)
	}

	// Bob should succeed in adding a new HTLC since a previous HTLC was just
	// failed. We use numHTLCs here since the previous AddHTLC with this index
	// failed.
	htlc, _ = createHTLC(numHTLCs, htlcAmt)
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)

	// Add a commitment to Bob's commitment chain.
	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign next commitment")
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err, "unable to recv new commitment")

	// The next HTLC should fail with ErrMaxHTLCNumber. The index is incremented
	// by one.
	htlc, _ = createHTLC(numHTLCs+1, htlcAmt)
	if _, err = aliceChannel.AddHTLC(htlc, nil); err != ErrMaxHTLCNumber {
		t.Fatalf("expected ErrMaxHTLCNumber, instead received: %v", err)
	}

	// Likewise, Bob should not be able to receive this HTLC if Alice can't
	// add it.
	if _, err := bobChannel.ReceiveHTLC(htlc); err != ErrMaxHTLCNumber {
		t.Fatalf("expected ErrMaxHTLCNumber, instead received: %v", err)
	}
}

// TestMaxAsynchronousHtlcs tests that Bob correctly receives (and does not
// fail) an HTLC from Alice when exchanging asynchronous payments. We want to
// mimic the following case where Bob's commitment transaction is full before
// starting:
//
//	Alice                    Bob
//
// 1.         <---settle/fail---
// 2.         <-------sig-------
// 3.         --------sig------> (covers an add sent before step 1)
// 4.         <-------rev-------
// 5.         --------rev------>
// 6.         --------add------>
// 7.         - - - - sig - - ->
// This represents an asynchronous commitment dance in which both sides are
// sending signatures at the same time. In step 3, the signature does not
// cover the recent settle/fail that Bob sent in step 1. However, the add that
// Alice sends to Bob in step 6 does not overflow Bob's commitment transaction.
// This is because validateCommitmentSanity counts the HTLC's by ignoring
// HTLC's which will be removed in the next signature that Alice sends. Thus,
// the add won't overflow. This is because the signature received in step 7
// covers the settle/fail in step 1 and makes space for the add in step 6.
func TestMaxAsynchronousHtlcs(t *testing.T) {
	t.Parallel()

	// We'll kick off the test by creating our channels which both are
	// loaded with 5 BTC each.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// One over the maximum number of HTLCs that either can accept.
	const numHTLCs = 12

	// Set the remote's required MaxAcceptedHtlcs. This means that Alice
	// can only offer the remote up to numHTLCs HTLCs.
	aliceChannel.channelState.LocalChanCfg.MaxAcceptedHtlcs = numHTLCs
	bobChannel.channelState.RemoteChanCfg.MaxAcceptedHtlcs = numHTLCs

	// Similarly, set the remote config's MaxAcceptedHtlcs. This means
	// that the remote will be aware that Bob will only accept up to
	// numHTLCs at a time.
	aliceChannel.channelState.RemoteChanCfg.MaxAcceptedHtlcs = numHTLCs
	bobChannel.channelState.LocalChanCfg.MaxAcceptedHtlcs = numHTLCs

	// Each HTLC amount is 0.1 BTC.
	htlcAmt := lnwire.NewMSatFromSatoshis(0.1 * btcutil.SatoshiPerBitcoin)

	var htlcID uint64

	// Send the maximum allowed number of HTLCs minus one.
	for i := 0; i < numHTLCs-1; i++ {
		htlc, _ := createHTLC(i, htlcAmt)
		addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)

		// Just assign htlcID to the last received HTLC.
		htlcID = htlc.ID
	}

	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("unable to transition state: %v", err)
	}

	// Send an HTLC to Bob so that Bob's commitment transaction is full.
	htlc, _ := createHTLC(numHTLCs-1, htlcAmt)
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)

	// Fail back an HTLC and sign a commitment as in steps 1 & 2.
	err = bobChannel.FailHTLC(htlcID, []byte{}, nil, nil, nil)
	require.NoError(t, err, "unable to fail htlc")

	if err := aliceChannel.ReceiveFailHTLC(htlcID, []byte{}); err != nil {
		t.Fatalf("unable to receive fail htlc: %v", err)
	}

	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign next commitment")

	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err, "unable to receive new commitment")

	// Cover the HTLC referenced with id equal to numHTLCs-1 with a new
	// signature (step 3).
	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign next commitment")

	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err, "unable to receive new commitment")

	// Both sides exchange revocations as in step 4 & 5.
	bobRevocation, _, _, err := bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to revoke revocation")

	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err, "unable to receive revocation")

	aliceRevocation, _, _, err := aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to revoke revocation")

	_, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err, "unable to receive revocation")

	// Send the final Add which should succeed as in step 6.
	htlc, _ = createHTLC(numHTLCs, htlcAmt)
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)

	// Receiving the commitment should succeed as in step 7 since space was
	// made.
	aliceNewCommit, err = aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign next commitment")

	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err, "unable to receive new commitment")
}

// TestMaxPendingAmount tests that the maximum overall pending HTLC value is met
// given several HTLCs that, combined, exceed this value. An ErrMaxPendingAmount
// error should be returned.
func TestMaxPendingAmount(t *testing.T) {
	t.Parallel()

	// We'll kick off the test by creating our channels which both are
	// loaded with 5 BTC each.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// We set the remote required MaxPendingAmount to 3 BTC. We will
	// attempt to overflow this value and see if it gives us the
	// ErrMaxPendingAmount error.
	maxPending := lnwire.NewMSatFromSatoshis(btcutil.SatoshiPerBitcoin * 3)

	// We set the max pending amount of Alice's config. This mean that she
	// cannot offer Bob HTLCs with a total value above this limit at a given
	// time.
	aliceChannel.channelState.LocalChanCfg.MaxPendingAmount = maxPending
	bobChannel.channelState.RemoteChanCfg.MaxPendingAmount = maxPending

	// First, we'll add 2 HTLCs of 1.5 BTC each to Alice's commitment.
	// This won't trigger Alice's ErrMaxPendingAmount error.
	const numHTLCs = 2
	htlcAmt := lnwire.NewMSatFromSatoshis(1.5 * btcutil.SatoshiPerBitcoin)
	for i := 0; i < numHTLCs; i++ {
		htlc, _ := createHTLC(i, htlcAmt)
		addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)
	}

	// We finally add one more HTLC of 0.1 BTC to Alice's commitment. This
	// SHOULD trigger Alice's ErrMaxPendingAmount error.
	htlcAmt = lnwire.NewMSatFromSatoshis(0.1 * btcutil.SatoshiPerBitcoin)
	htlc, _ := createHTLC(numHTLCs, htlcAmt)
	_, err = aliceChannel.AddHTLC(htlc, nil)
	if err != ErrMaxPendingAmount {
		t.Fatalf("expected ErrMaxPendingAmount, instead received: %v", err)
	}

	// And also Bob shouldn't be accepting this HTLC upon calling ReceiveHTLC.
	if _, err := bobChannel.ReceiveHTLC(htlc); err != ErrMaxPendingAmount {
		t.Fatalf("expected ErrMaxPendingAmount, instead received: %v", err)
	}
}

func assertChannelBalances(t *testing.T, alice, bob *LightningChannel,
	aliceBalance, bobBalance btcutil.Amount) {

	_, _, line, _ := runtime.Caller(1)

	aliceSelfBalance := alice.channelState.LocalCommitment.LocalBalance.ToSatoshis()
	aliceBobBalance := alice.channelState.LocalCommitment.RemoteBalance.ToSatoshis()
	if aliceSelfBalance != aliceBalance {
		t.Fatalf("line #%v: wrong alice self balance: expected %v, got %v",
			line, aliceBalance, aliceSelfBalance)
	}
	if aliceBobBalance != bobBalance {
		t.Fatalf("line #%v: wrong alice bob's balance: expected %v, got %v",
			line, bobBalance, aliceBobBalance)
	}

	bobSelfBalance := bob.channelState.LocalCommitment.LocalBalance.ToSatoshis()
	bobAliceBalance := bob.channelState.LocalCommitment.RemoteBalance.ToSatoshis()
	if bobSelfBalance != bobBalance {
		t.Fatalf("line #%v: wrong bob self balance: expected %v, got %v",
			line, bobBalance, bobSelfBalance)
	}
	if bobAliceBalance != aliceBalance {
		t.Fatalf("line #%v: wrong alice bob's balance: expected %v, got %v",
			line, aliceBalance, bobAliceBalance)
	}
}

// TestChanReserve tests that the ErrBelowChanReserve error is thrown when an
// HTLC is added that causes a node's balance to dip below its channel reserve
// limit.
func TestChanReserve(t *testing.T) {
	t.Parallel()

	setupChannels := func() (*LightningChannel, *LightningChannel) {
		// We'll kick off the test by creating our channels which both
		// are loaded with 5 BTC each.
		aliceChannel, bobChannel, err := CreateTestChannels(
			t, channeldb.SingleFunderTweaklessBit,
		)
		if err != nil {
			t.Fatalf("unable to create test channels: %v", err)
		}

		// We set the remote required ChanReserve to 0.5 BTC. We will
		// attempt to cause Alice's balance to dip below this amount
		// and test whether it triggers the ErrBelowChanReserve error.
		aliceMinReserve := btcutil.Amount(0.5 *
			btcutil.SatoshiPerBitcoin)

		// Alice will need to keep her reserve above aliceMinReserve,
		// so set this limit to here local config.
		aliceChannel.channelState.LocalChanCfg.ChanReserve = aliceMinReserve

		// During channel opening Bob will also get to know Alice's
		// minimum reserve, and this will be found in his remote
		// config.
		bobChannel.channelState.RemoteChanCfg.ChanReserve = aliceMinReserve

		// We set Bob's channel reserve to a value that is larger than
		// his current balance in the channel. This will ensure that
		// after a channel is first opened, Bob can still receive HTLCs
		// even though his balance is less than his channel reserve.
		bobMinReserve := btcutil.Amount(6 * btcutil.SatoshiPerBitcoin)
		bobChannel.channelState.LocalChanCfg.ChanReserve = bobMinReserve
		aliceChannel.channelState.RemoteChanCfg.ChanReserve = bobMinReserve

		return aliceChannel, bobChannel
	}
	aliceChannel, bobChannel := setupChannels()

	aliceIndex := 0
	bobIndex := 0

	// Add an HTLC that will increase Bob's balance. This should succeed,
	// since Alice stays above her channel reserve, and Bob increases his
	// balance (while still being below his channel reserve).
	//
	// Resulting balances:
	//	Alice:	4.5
	//	Bob:	5.0
	htlcAmt := lnwire.NewMSatFromSatoshis(0.5 * btcutil.SatoshiPerBitcoin)
	htlc, _ := createHTLC(aliceIndex, htlcAmt)
	aliceIndex++
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)

	// Force a state transition, making sure this HTLC is considered valid
	// even though the channel reserves are not met.
	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("unable to complete state update: %v", err)
	}

	commitFee := aliceChannel.channelState.LocalCommitment.CommitFee
	assertChannelBalances(
		t, aliceChannel, bobChannel,
		btcutil.SatoshiPerBitcoin*4.5-commitFee, btcutil.SatoshiPerBitcoin*5,
	)

	// Now let Bob try to add an HTLC. This should fail, since it will
	// decrease his balance, which is already below the channel reserve.
	//
	// Resulting balances:
	//	Alice:	4.5
	//	Bob:	5.0
	htlc, _ = createHTLC(bobIndex, htlcAmt)
	bobIndex++
	_, err := bobChannel.AddHTLC(htlc, nil)
	require.ErrorIs(t, err, ErrBelowChanReserve)

	// Alice will reject this htlc upon receiving the htlc.
	_, err = aliceChannel.ReceiveHTLC(htlc)
	require.ErrorIs(t, err, ErrBelowChanReserve)

	// We must setup the channels again, since a violation of the channel
	// constraints leads to channel shutdown.
	aliceChannel, bobChannel = setupChannels()

	aliceIndex = 0
	bobIndex = 0

	// Now we'll add HTLC of 3.5 BTC to Alice's commitment, this should put
	// Alice's balance at 1.5 BTC.
	//
	// Resulting balances:
	//	Alice:	1.5
	//	Bob:	9.5
	htlcAmt = lnwire.NewMSatFromSatoshis(3.5 * btcutil.SatoshiPerBitcoin)

	// The first HTLC should successfully be sent.
	htlc, _ = createHTLC(aliceIndex, htlcAmt)
	aliceIndex++
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)

	// Add a second HTLC of 1 BTC. This should fail because it will take
	// Alice's balance all the way down to her channel reserve, but since
	// she is the initiator the additional transaction fee makes her
	// balance dip below.
	htlcAmt = lnwire.NewMSatFromSatoshis(1 * btcutil.SatoshiPerBitcoin)
	htlc, _ = createHTLC(aliceIndex, htlcAmt)
	aliceIndex++
	_, err = aliceChannel.AddHTLC(htlc, nil)
	require.ErrorIs(t, err, ErrBelowChanReserve)

	// Likewise, Bob will reject receiving the htlc because of the same reason.
	_, err = bobChannel.ReceiveHTLC(htlc)
	require.ErrorIs(t, err, ErrBelowChanReserve)

	// We must setup the channels again, since a violation of the channel
	// constraints leads to channel shutdown.
	aliceChannel, bobChannel = setupChannels()

	aliceIndex = 0
	bobIndex = 0

	// Add a HTLC of 2 BTC to Alice, and the settle it.
	// Resulting balances:
	//	Alice:	3.0
	//	Bob:	7.0
	htlcAmt = lnwire.NewMSatFromSatoshis(2 * btcutil.SatoshiPerBitcoin)
	htlc, preimage := createHTLC(aliceIndex, htlcAmt)
	aliceIndex++
	aliceHtlcIndex, err := aliceChannel.AddHTLC(htlc, nil)
	require.NoError(t, err, "unable to add htlc")
	bobHtlcIndex, err := bobChannel.ReceiveHTLC(htlc)
	require.NoError(t, err, "unable to recv htlc")
	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("unable to complete state update: %v", err)
	}

	commitFee = aliceChannel.channelState.LocalCommitment.CommitFee
	assertChannelBalances(
		t, aliceChannel, bobChannel,
		btcutil.SatoshiPerBitcoin*3-commitFee, btcutil.SatoshiPerBitcoin*5,
	)

	if err := bobChannel.SettleHTLC(preimage, bobHtlcIndex, nil, nil, nil); err != nil {
		t.Fatalf("bob unable to settle inbound htlc: %v", err)
	}
	if err := aliceChannel.ReceiveHTLCSettle(preimage, aliceHtlcIndex); err != nil {
		t.Fatalf("alice unable to accept settle of outbound htlc: %v", err)
	}
	if err := ForceStateTransition(bobChannel, aliceChannel); err != nil {
		t.Fatalf("unable to complete state update: %v", err)
	}

	commitFee = aliceChannel.channelState.LocalCommitment.CommitFee
	assertChannelBalances(
		t, aliceChannel, bobChannel,
		btcutil.SatoshiPerBitcoin*3-commitFee, btcutil.SatoshiPerBitcoin*7,
	)

	// And now let Bob add an HTLC of 1 BTC. This will take Bob's balance
	// all the way down to his channel reserve, but since he is not paying
	// the fee this is okay.
	htlcAmt = lnwire.NewMSatFromSatoshis(1 * btcutil.SatoshiPerBitcoin)
	htlc, _ = createHTLC(bobIndex, htlcAmt)
	bobIndex++
	addAndReceiveHTLC(t, bobChannel, aliceChannel, htlc, nil)

	// Do a last state transition, which should succeed.
	if err := ForceStateTransition(bobChannel, aliceChannel); err != nil {
		t.Fatalf("unable to complete state update: %v", err)
	}

	commitFee = aliceChannel.channelState.LocalCommitment.CommitFee
	assertChannelBalances(
		t, aliceChannel, bobChannel,
		btcutil.SatoshiPerBitcoin*3-commitFee, btcutil.SatoshiPerBitcoin*6,
	)
}

// TestChanReserveRemoteInitiator tests that the channel reserve of the
// initiator is accounted for when adding HTLCs, whether the initiator is the
// local or remote node.
func TestChanReserveRemoteInitiator(t *testing.T) {
	t.Parallel()

	// We start out with a channel where both parties have 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	if err != nil {
		t.Fatal(err)
	}

	// Set Alice's channel reserve to be 5 BTC-commitfee. This means she
	// has just enough balance to cover the comitment fee, but not enough
	// to add any more HTLCs to the commitment. Although a reserve this
	// high is unrealistic, a channel can easily get into a situation
	// where the initiator cannot pay for the fee of any more HTLCs.
	commitFee := aliceChannel.channelState.LocalCommitment.CommitFee
	aliceMinReserve := 5*btcutil.SatoshiPerBitcoin - commitFee

	aliceChannel.channelState.LocalChanCfg.ChanReserve = aliceMinReserve
	bobChannel.channelState.RemoteChanCfg.ChanReserve = aliceMinReserve

	// Now let Bob attempt to add an HTLC of 0.1 BTC. He has plenty of
	// money available to spend, but Alice, which is the initiator, cannot
	// afford any more HTLCs on the commitment transaction because that
	// would take here below her channel reserve..
	htlcAmt := lnwire.NewMSatFromSatoshis(0.1 * btcutil.SatoshiPerBitcoin)
	htlc, _ := createHTLC(0, htlcAmt)

	// Bob should refuse to add this HTLC, since he realizes it will create
	// an invalid commitment.
	_, err = bobChannel.AddHTLC(htlc, nil)
	require.ErrorIs(t, err, ErrBelowChanReserve)

	// Of course Alice will also not have enough balance to add it herself.
	_, err = aliceChannel.AddHTLC(htlc, nil)
	require.ErrorIs(t, err, ErrBelowChanReserve)

	// Same for Alice, she should refuse to accept this second HTLC.
	_, err = aliceChannel.ReceiveHTLC(htlc)
	require.ErrorIs(t, err, ErrBelowChanReserve)
}

// TestChanReserveLocalInitiatorDustHtlc tests that fee the initiator must pay
// when adding HTLCs is accounted for, even though the HTLC is considered dust
// by the remote bode.
func TestChanReserveLocalInitiatorDustHtlc(t *testing.T) {
	t.Parallel()

	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	if err != nil {
		t.Fatal(err)
	}

	// The amount of the HTLC should not be considered dust according to
	// Alice's dust limit (200 sat), but be dust according to Bob's dust
	// limit (1300 sat). It is considered dust if the amount remaining
	// after paying the HTLC fee is below the dustlimit, so we choose a
	// size of 500+htlcFee.
	htlcSat := btcutil.Amount(500) + HtlcTimeoutFee(
		aliceChannel.channelState.ChanType,
		chainfee.SatPerKWeight(
			aliceChannel.channelState.LocalCommitment.FeePerKw,
		),
	)

	// Set Alice's channel reserve to be low enough to carry the value of
	// the HTLC, but not low enough to allow the extra fee from adding the
	// HTLC to the commitment.
	commitFee := aliceChannel.channelState.LocalCommitment.CommitFee
	aliceMinReserve := 5*btcutil.SatoshiPerBitcoin - commitFee - htlcSat

	aliceChannel.channelState.LocalChanCfg.ChanReserve = aliceMinReserve
	bobChannel.channelState.RemoteChanCfg.ChanReserve = aliceMinReserve

	htlcDustAmt := lnwire.NewMSatFromSatoshis(htlcSat)
	htlc, _ := createHTLC(0, htlcDustAmt)

	// Alice should realize that the fee she must pay to add this HTLC to
	// the local commitment would take her below the channel reserve.
	_, err = aliceChannel.AddHTLC(htlc, nil)
	require.ErrorIs(t, err, ErrBelowChanReserve)
}

// TestMinHTLC tests that the ErrBelowMinHTLC error is thrown if an HTLC is added
// that is below the minimm allowed value for HTLCs.
func TestMinHTLC(t *testing.T) {
	t.Parallel()

	// We'll kick off the test by creating our channels which both are
	// loaded with 5 BTC each.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// We set Alice's MinHTLC to 0.1 BTC. We will attempt to send an
	// HTLC BELOW this value to trigger the ErrBelowMinHTLC error.
	minValue := lnwire.NewMSatFromSatoshis(0.1 * btcutil.SatoshiPerBitcoin)

	// Setting the min value in Alice's local config means that the
	// remote will not accept any HTLCs of value less than specified.
	aliceChannel.channelState.LocalChanCfg.MinHTLC = minValue
	bobChannel.channelState.RemoteChanCfg.MinHTLC = minValue

	// First, we will add an HTLC of 0.5 BTC. This will not trigger
	// ErrBelowMinHTLC.
	htlcAmt := lnwire.NewMSatFromSatoshis(0.5 * btcutil.SatoshiPerBitcoin)
	htlc, _ := createHTLC(0, htlcAmt)
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)

	// We add an HTLC below the min value, this should result in
	// an ErrBelowMinHTLC error.
	amt := minValue - 100
	htlc, _ = createHTLC(1, amt)
	_, err = aliceChannel.AddHTLC(htlc, nil)
	if err != ErrBelowMinHTLC {
		t.Fatalf("expected ErrBelowMinHTLC, instead received: %v", err)
	}

	// Bob will receive this HTLC, but reject the next received htlc, since
	// the htlc is too small.
	_, err = bobChannel.ReceiveHTLC(htlc)
	if err != ErrBelowMinHTLC {
		t.Fatalf("expected ErrBelowMinHTLC, instead received: %v", err)
	}
}

// TestInvalidHTLCAmt tests that ErrInvalidHTLCAmt is returned when trying to
// add HTLCs that don't carry a positive value.
func TestInvalidHTLCAmt(t *testing.T) {
	t.Parallel()

	// We'll kick off the test by creating our channels which both are
	// loaded with 5 BTC each.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// We'll set the min HTLC values for each party to zero, which
	// technically would permit zero-value HTLCs.
	aliceChannel.channelState.LocalChanCfg.MinHTLC = 0
	bobChannel.channelState.RemoteChanCfg.MinHTLC = 0

	// Create a zero-value HTLC.
	htlcAmt := lnwire.MilliSatoshi(0)
	htlc, _ := createHTLC(0, htlcAmt)

	// Sending or receiving the HTLC should fail with ErrInvalidHTLCAmt.
	_, err = aliceChannel.AddHTLC(htlc, nil)
	if err != ErrInvalidHTLCAmt {
		t.Fatalf("expected ErrInvalidHTLCAmt, got: %v", err)
	}
	_, err = bobChannel.ReceiveHTLC(htlc)
	if err != ErrInvalidHTLCAmt {
		t.Fatalf("expected ErrInvalidHTLCAmt, got: %v", err)
	}
}

// TestNewBreachRetributionSkipsDustHtlcs ensures that in the case of a
// contract breach, all dust HTLCs are ignored and not reflected in the
// produced BreachRetribution struct. We ignore these HTLCs as they aren't
// actually manifested on the commitment transaction, as a result we can't
// actually revoked them.
func TestNewBreachRetributionSkipsDustHtlcs(t *testing.T) {
	t.Parallel()

	// We'll kick off the test by creating our channels which both are
	// loaded with 5 BTC each.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	var fakeOnionBlob [lnwire.OnionPacketSize]byte
	copy(fakeOnionBlob[:], bytes.Repeat([]byte{0x05}, lnwire.OnionPacketSize))

	// We'll modify the dust settings on both channels to be a predictable
	// value for the prurpose of the test.
	dustValue := btcutil.Amount(200)
	aliceChannel.channelState.LocalChanCfg.DustLimit = dustValue
	aliceChannel.channelState.RemoteChanCfg.DustLimit = dustValue
	bobChannel.channelState.LocalChanCfg.DustLimit = dustValue
	bobChannel.channelState.RemoteChanCfg.DustLimit = dustValue

	// We'll now create a series of dust HTLC's, and send then from Alice
	// to Bob, finally locking both of them in.
	var bobPreimage [32]byte
	copy(bobPreimage[:], bytes.Repeat([]byte{0xbb}, 32))
	for i := 0; i < 3; i++ {
		rHash := sha256.Sum256(bobPreimage[:])
		h := &lnwire.UpdateAddHTLC{
			PaymentHash: rHash,
			Amount:      lnwire.NewMSatFromSatoshis(dustValue),
			Expiry:      uint32(10),
			OnionBlob:   fakeOnionBlob,
		}

		htlcIndex, err := aliceChannel.AddHTLC(h, nil)
		if err != nil {
			t.Fatalf("unable to add bob's htlc: %v", err)
		}

		h.ID = htlcIndex
		if _, err := bobChannel.ReceiveHTLC(h); err != nil {
			t.Fatalf("unable to recv bob's htlc: %v", err)
		}
	}

	// With the HTLC's applied to both update logs, we'll initiate a state
	// transition from Alice.
	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("unable to complete alice's state transition: %v", err)
	}

	// At this point, we'll capture the current state number, as well as
	// the current commitment.
	revokedStateNum := aliceChannel.channelState.LocalCommitment.CommitHeight

	// We'll now have Bob settle those HTLC's to Alice and then advance
	// forward to a new state.
	for i := 0; i < 3; i++ {
		err := bobChannel.SettleHTLC(bobPreimage, uint64(i), nil, nil, nil)
		if err != nil {
			t.Fatalf("unable to settle htlc: %v", err)
		}
		err = aliceChannel.ReceiveHTLCSettle(bobPreimage, uint64(i))
		if err != nil {
			t.Fatalf("unable to settle htlc: %v", err)
		}
	}
	if err := ForceStateTransition(bobChannel, aliceChannel); err != nil {
		t.Fatalf("unable to complete bob's state transition: %v", err)
	}

	// At this point, we'll now simulate a contract breach by Bob using the
	// NewBreachRetribution method.
	breachTx := aliceChannel.channelState.RemoteCommitment.CommitTx
	breachRet, err := NewBreachRetribution(
		aliceChannel.channelState, revokedStateNum, 100, breachTx,
		fn.Some[AuxLeafStore](&MockAuxLeafStore{}),
		fn.Some[AuxContractResolver](&MockAuxContractResolver{}),
	)
	require.NoError(t, err, "unable to create breach retribution")

	// The retribution shouldn't have any HTLCs set as they were all below
	// dust for both parties.
	if len(breachRet.HtlcRetributions) != 0 {
		t.Fatalf("zero HTLC retributions should have been created, "+
			"instead %v were", len(breachRet.HtlcRetributions))
	}
}

// compareHtlcs compares two paymentDescriptors.
func compareHtlcs(htlc1, htlc2 *paymentDescriptor) error {
	if htlc1.LogIndex != htlc2.LogIndex {
		return fmt.Errorf("htlc log index did not match")
	}
	if htlc1.HtlcIndex != htlc2.HtlcIndex {
		return fmt.Errorf("htlc index did not match")
	}
	if htlc1.ParentIndex != htlc2.ParentIndex {
		return fmt.Errorf("htlc parent index did not match")
	}

	if htlc1.RHash != htlc2.RHash {
		return fmt.Errorf("htlc rhash did not match")
	}
	return nil
}

// compareIndexes is a helper method to compare two index maps.
func compareIndexes(a, b map[uint64]*fn.Node[*paymentDescriptor]) error {
	for k1, e1 := range a {
		e2, ok := b[k1]
		if !ok {
			return fmt.Errorf("element with key %d "+
				"not found in b", k1)
		}
		htlc1, htlc2 := e1.Value, e2.Value
		if err := compareHtlcs(htlc1, htlc2); err != nil {
			return err
		}
	}

	for k1, e1 := range b {
		e2, ok := a[k1]
		if !ok {
			return fmt.Errorf("element with key %d not "+
				"found in a", k1)
		}
		htlc1, htlc2 := e1.Value, e2.Value
		if err := compareHtlcs(htlc1, htlc2); err != nil {
			return err
		}
	}

	return nil
}

// compareLogs is a helper method to compare two updateLogs.
func compareLogs(a, b *updateLog) error {
	if a.logIndex != b.logIndex {
		return fmt.Errorf("log indexes don't match: %d vs %d",
			a.logIndex, b.logIndex)
	}

	if a.htlcCounter != b.htlcCounter {
		return fmt.Errorf("htlc counters don't match: %d vs %d",
			a.htlcCounter, b.htlcCounter)
	}

	if err := compareIndexes(a.updateIndex, b.updateIndex); err != nil {
		return fmt.Errorf("update indexes don't match: %w", err)
	}
	if err := compareIndexes(a.htlcIndex, b.htlcIndex); err != nil {
		return fmt.Errorf("htlc indexes don't match: %w", err)
	}

	if a.Len() != b.Len() {
		return fmt.Errorf("list lengths not equal: %d vs %d",
			a.Len(), b.Len())
	}

	e1, e2 := a.Front(), b.Front()
	for ; e1 != nil; e1, e2 = e1.Next(), e2.Next() {
		htlc1, htlc2 := e1.Value, e2.Value
		if err := compareHtlcs(htlc1, htlc2); err != nil {
			return err
		}
	}

	return nil
}

// TestChannelRestoreUpdateLogs makes sure we are able to properly restore the
// update logs in the case where a different number of HTLCs are locked in on
// the local, remote and pending remote commitment.
func TestChannelRestoreUpdateLogs(t *testing.T) {
	t.Parallel()

	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// First, we'll add an HTLC from Alice to Bob, which we will lock in on
	// Bob's commit, but not on Alice's.
	htlcAmount := lnwire.NewMSatFromSatoshis(20000)
	htlcAlice, _ := createHTLC(0, htlcAmount)
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlcAlice, nil)

	// Let Alice sign a new state, which will include the HTLC just sent.
	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign commitment")

	// Bob receives this commitment signature, and revokes his old state.
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err, "unable to receive commitment")
	bobRevocation, _, _, err := bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to revoke commitment")

	// When Alice now receives this revocation, she will advance her remote
	// commitment chain to the commitment which includes the HTLC just
	// sent. However her local commitment chain still won't include the
	// state with the HTLC, since she hasn't received a new commitment
	// signature from Bob yet.
	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err, "unable to receive revocation")

	// Now make Alice send and sign an additional HTLC. We don't let Bob
	// receive it. We do this since we want to check that update logs are
	// restored properly below, and we'll only restore updates that have
	// been ACKed.
	htlcAlice, _ = createHTLC(1, htlcAmount)
	if _, err := aliceChannel.AddHTLC(htlcAlice, nil); err != nil {
		t.Fatalf("alice unable to add htlc: %v", err)
	}

	// Send the signature covering the HTLC. This is okay, since the local
	// and remote commit chains are updated in an async fashion. Since the
	// remote chain was updated with the latest state (since Bob sent the
	// revocation earlier) we can keep advancing the remote commit chain.
	aliceNewCommit, err = aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign commitment")

	// After Alice has signed this commitment, her local commitment will
	// contain no HTLCs, her remote commitment will contain an HTLC with
	// index 0, and the pending remote commitment (a signed remote
	// commitment which is not AKCed yet) will contain an additional HTLC
	// with index 1.

	// We now re-create the channels, mimicking a restart. This should sync
	// the update logs up to the correct state set up above.
	newAliceChannel, err := NewLightningChannel(
		aliceChannel.Signer, aliceChannel.channelState,
		aliceChannel.sigPool,
	)
	require.NoError(t, err, "unable to create new channel")

	newBobChannel, err := NewLightningChannel(
		bobChannel.Signer, bobChannel.channelState,
		bobChannel.sigPool,
	)
	require.NoError(t, err, "unable to create new channel")

	// compare all the logs between the old and new channels, to make sure
	// they all got restored properly.
	err = compareLogs(aliceChannel.updateLogs.Local,
		newAliceChannel.updateLogs.Local)
	require.NoError(t, err, "alice local log not restored")

	err = compareLogs(aliceChannel.updateLogs.Remote,
		newAliceChannel.updateLogs.Remote)
	require.NoError(t, err, "alice remote log not restored")

	err = compareLogs(bobChannel.updateLogs.Local,
		newBobChannel.updateLogs.Local)
	require.NoError(t, err, "bob local log not restored")

	err = compareLogs(bobChannel.updateLogs.Remote,
		newBobChannel.updateLogs.Remote)
	require.NoError(t, err, "bob remote log not restored")
}

// fetchNumUpdates counts the number of updateType in the log.
func fetchNumUpdates(t updateType, log *updateLog) int {
	num := 0
	for e := log.Front(); e != nil; e = e.Next() {
		htlc := e.Value
		if htlc.EntryType == t {
			num++
		}
	}
	return num
}

// assertInLog checks that the given log contains the expected number of Adds
// and Fails.
func assertInLog(t *testing.T, log *updateLog, numAdds, numFails int) {
	adds := fetchNumUpdates(Add, log)
	if adds != numAdds {
		t.Fatalf("expected %d adds, found %d", numAdds, adds)
	}
	fails := fetchNumUpdates(Fail, log)
	if fails != numFails {
		t.Fatalf("expected %d fails, found %d", numFails, fails)
	}
}

// assertInLogs asserts that the expected number of Adds and Fails occurs in
// the local and remote update log of the given channel.
func assertInLogs(t *testing.T, channel *LightningChannel, numAddsLocal,
	numFailsLocal, numAddsRemote, numFailsRemote int) {

	assertInLog(t, channel.updateLogs.Local, numAddsLocal, numFailsLocal)
	assertInLog(t, channel.updateLogs.Remote, numAddsRemote, numFailsRemote)
}

// restoreAndAssert creates a new LightningChannel from the given channel's
// state, and asserts that the new channel has had its logs restored to the
// expected state.
func restoreAndAssert(t *testing.T, channel *LightningChannel, numAddsLocal,
	numFailsLocal, numAddsRemote, numFailsRemote int) {

	newChannel, err := NewLightningChannel(
		channel.Signer, channel.channelState,
		channel.sigPool,
	)
	require.NoError(t, err, "unable to create new channel")

	assertInLog(t, newChannel.updateLogs.Local, numAddsLocal, numFailsLocal)
	assertInLog(
		t, newChannel.updateLogs.Remote, numAddsRemote, numFailsRemote,
	)
}

// TestChannelRestoreUpdateLogsFailedHTLC runs through a scenario where an
// HTLC is added and failed, and asserts along the way that we would restore
// the update logs of the channel to the expected state at any point.
func TestChannelRestoreUpdateLogsFailedHTLC(t *testing.T) {
	t.Parallel()

	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// First, we'll add an HTLC from Alice to Bob, and lock it in for both.
	htlcAmount := lnwire.NewMSatFromSatoshis(20000)
	htlcAlice, _ := createHTLC(0, htlcAmount)
	if _, err := aliceChannel.AddHTLC(htlcAlice, nil); err != nil {
		t.Fatalf("alice unable to add htlc: %v", err)
	}
	// The htlc Alice sent should be in her local update log.
	assertInLogs(t, aliceChannel, 1, 0, 0, 0)

	// A restore at this point should NOT restore this update, as it is not
	// locked in anywhere yet.
	restoreAndAssert(t, aliceChannel, 0, 0, 0, 0)

	if _, err := bobChannel.ReceiveHTLC(htlcAlice); err != nil {
		t.Fatalf("bob unable to recv add htlc: %v", err)
	}

	// Lock in the Add on both sides.
	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("unable to complete state update: %v", err)
	}

	// Since it is locked in, Alice should have the Add in the local log,
	// and it should be restored during restoration.
	assertInLogs(t, aliceChannel, 1, 0, 0, 0)
	restoreAndAssert(t, aliceChannel, 1, 0, 0, 0)

	// Now we make Bob fail this HTLC.
	err = bobChannel.FailHTLC(0, []byte("failreason"), nil, nil, nil)
	require.NoError(t, err, "unable to cancel HTLC")

	err = aliceChannel.ReceiveFailHTLC(0, []byte("failreason"))
	require.NoError(t, err, "unable to recv htlc cancel")

	// This Fail update should have been added to Alice's remote update log.
	assertInLogs(t, aliceChannel, 1, 0, 0, 1)

	// Restoring should restore the HTLC added to Alice's local log, but
	// NOT the Fail sent by Bob, since it is not locked in.
	restoreAndAssert(t, aliceChannel, 1, 0, 0, 0)

	// Bob sends a signature.
	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign commitment")
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err, "unable to receive commitment")

	// When Alice receives Bob's new commitment, the logs will stay the
	// same until she revokes her old state. The Fail will still not be
	// restored during a restoration.
	assertInLogs(t, aliceChannel, 1, 0, 0, 1)
	restoreAndAssert(t, aliceChannel, 1, 0, 0, 0)

	aliceRevocation, _, _, err := aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to revoke commitment")
	_, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err, "bob unable to process alice's revocation")

	// At this point Alice has advanced her local commitment chain to a
	// commitment with no HTLCs left. The current state on her remote
	// commitment chain, however, still has the HTLC active, as she hasn't
	// sent a new signature yet. If we'd now restart and restore, the htlc
	// failure update should still be waiting for inclusion in Alice's next
	// signature. Otherwise the produced signature would be invalid.
	assertInLogs(t, aliceChannel, 1, 0, 0, 1)
	restoreAndAssert(t, aliceChannel, 1, 0, 0, 1)

	// Now send a signature from Alice. This will give Bob a new commitment
	// where the HTLC is removed.
	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign commitment")
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err, "unable to receive commitment")

	// When sending a new commitment, Alice will add a pending commit to
	// her remote chain. Since the unsigned acked updates aren't deleted
	// until we receive a revocation, the fail should still be present.
	assertInLogs(t, aliceChannel, 1, 0, 0, 1)
	restoreAndAssert(t, aliceChannel, 1, 0, 0, 1)

	// When Alice receives Bob's revocation, the Fail is irrevocably locked
	// in on both sides. She should compact the logs, removing the HTLC and
	// the corresponding Fail from the local update log.
	bobRevocation, _, _, err := bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to revoke commitment")
	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err, "unable to receive revocation")

	assertInLogs(t, aliceChannel, 0, 0, 0, 0)
	restoreAndAssert(t, aliceChannel, 0, 0, 0, 0)
}

// TestDuplicateFailRejection tests that if either party attempts to fail an
// HTLC twice, then we'll reject the second fail attempt.
func TestDuplicateFailRejection(t *testing.T) {
	t.Parallel()

	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// First, we'll add an HTLC from Alice to Bob, and lock it in for both
	// parties.
	htlcAmount := lnwire.NewMSatFromSatoshis(20000)
	htlcAlice, _ := createHTLC(0, htlcAmount)
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlcAlice, nil)

	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("unable to complete state update: %v", err)
	}

	// With the HTLC locked in, we'll now have Bob fail the HTLC back to
	// Alice.
	err = bobChannel.FailHTLC(0, []byte("failreason"), nil, nil, nil)
	require.NoError(t, err, "unable to cancel HTLC")
	if err := aliceChannel.ReceiveFailHTLC(0, []byte("bad")); err != nil {
		t.Fatalf("unable to recv htlc cancel: %v", err)
	}

	// If we attempt to fail it AGAIN, then both sides should reject this
	// second failure attempt.
	err = bobChannel.FailHTLC(0, []byte("failreason"), nil, nil, nil)
	if err == nil {
		t.Fatalf("duplicate HTLC failure attempt should have failed")
	}
	if err := aliceChannel.ReceiveFailHTLC(0, []byte("bad")); err == nil {
		t.Fatalf("duplicate HTLC failure attempt should have failed")
	}

	// We'll now have Bob sign a new commitment to lock in the HTLC fail
	// for Alice.
	_, err = bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign commit")

	// We'll now force a restart for Bob and Alice, so we can test the
	// persistence related portion of this assertion.
	bobChannel, err = restartChannel(bobChannel)
	require.NoError(t, err, "unable to restart channel")
	aliceChannel, err = restartChannel(aliceChannel)
	require.NoError(t, err, "unable to restart channel")

	// If we try to fail the same HTLC again, then we should get an error.
	err = bobChannel.FailHTLC(0, []byte("failreason"), nil, nil, nil)
	if err == nil {
		t.Fatalf("duplicate HTLC failure attempt should have failed")
	}

	// Alice on the other hand should accept the failure again, as she
	// dropped all items in the logs which weren't committed.
	if err := aliceChannel.ReceiveFailHTLC(0, []byte("bad")); err != nil {
		t.Fatalf("unable to recv htlc cancel: %v", err)
	}
}

// TestDuplicateSettleRejection tests that if either party attempts to settle
// an HTLC twice, then we'll reject the second settle attempt.
func TestDuplicateSettleRejection(t *testing.T) {
	t.Parallel()

	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// First, we'll add an HTLC from Alice to Bob, and lock it in for both
	// parties.
	htlcAmount := lnwire.NewMSatFromSatoshis(20000)
	htlcAlice, alicePreimage := createHTLC(0, htlcAmount)
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlcAlice, nil)

	if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
		t.Fatalf("unable to complete state update: %v", err)
	}

	// With the HTLC locked in, we'll now have Bob settle the HTLC back to
	// Alice.
	err = bobChannel.SettleHTLC(alicePreimage, uint64(0), nil, nil, nil)
	require.NoError(t, err, "unable to cancel HTLC")
	err = aliceChannel.ReceiveHTLCSettle(alicePreimage, uint64(0))
	require.NoError(t, err, "unable to recv htlc cancel")

	// If we attempt to fail it AGAIN, then both sides should reject this
	// second failure attempt.
	err = bobChannel.SettleHTLC(alicePreimage, uint64(0), nil, nil, nil)
	if err == nil {
		t.Fatalf("duplicate HTLC failure attempt should have failed")
	}
	err = aliceChannel.ReceiveHTLCSettle(alicePreimage, uint64(0))
	if err == nil {
		t.Fatalf("duplicate HTLC failure attempt should have failed")
	}

	// We'll now have Bob sign a new commitment to lock in the HTLC fail
	// for Alice.
	_, err = bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign commit")

	// We'll now force a restart for Bob and Alice, so we can test the
	// persistence related portion of this assertion.
	bobChannel, err = restartChannel(bobChannel)
	require.NoError(t, err, "unable to restart channel")
	aliceChannel, err = restartChannel(aliceChannel)
	require.NoError(t, err, "unable to restart channel")

	// If we try to fail the same HTLC again, then we should get an error.
	err = bobChannel.SettleHTLC(alicePreimage, uint64(0), nil, nil, nil)
	if err == nil {
		t.Fatalf("duplicate HTLC failure attempt should have failed")
	}

	// Alice on the other hand should accept the failure again, as she
	// dropped all items in the logs which weren't committed.
	err = aliceChannel.ReceiveHTLCSettle(alicePreimage, uint64(0))
	require.NoError(t, err, "unable to recv htlc cancel")
}

// TestChannelRestoreCommitHeight tests that the local and remote commit
// heights of HTLCs are set correctly across restores.
func TestChannelRestoreCommitHeight(t *testing.T) {
	t.Parallel()

	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// helper method to check add heights of the htlcs found in the given
	// log after a restore.
	restoreAndAssertCommitHeights := func(t *testing.T,
		channel *LightningChannel, remoteLog bool, htlcIndex uint64,
		expLocal, expRemote uint64) *LightningChannel {

		newChannel, err := NewLightningChannel(
			channel.Signer, channel.channelState, channel.sigPool,
		)
		if err != nil {
			t.Fatalf("unable to create new channel: %v", err)
		}

		var pd *paymentDescriptor
		if remoteLog {
			h := newChannel.updateLogs.Local.lookupHtlc(htlcIndex)
			if h != nil {
				t.Fatalf("htlc found in wrong log")
			}
			pd = newChannel.updateLogs.Remote.lookupHtlc(htlcIndex)

		} else {
			h := newChannel.updateLogs.Remote.lookupHtlc(htlcIndex)
			if h != nil {
				t.Fatalf("htlc found in wrong log")
			}
			pd = newChannel.updateLogs.Local.lookupHtlc(htlcIndex)
		}
		if pd == nil {
			t.Fatalf("htlc not found in log")
		}

		if pd.addCommitHeights.Local != expLocal {
			t.Fatalf("expected local add height to be %d, was %d",
				expLocal, pd.addCommitHeights.Local)
		}
		if pd.addCommitHeights.Remote != expRemote {
			t.Fatalf("expected remote add height to be %d, was %d",
				expRemote, pd.addCommitHeights.Remote)
		}
		return newChannel
	}

	// We'll send an HtLC from Alice to Bob.
	htlcAmount := lnwire.NewMSatFromSatoshis(100000000)
	htlcAlice, _ := createHTLC(0, htlcAmount)
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlcAlice, nil)

	// Let Alice sign a new state, which will include the HTLC just sent.
	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign commitment")

	// The HTLC should only be on the pending remote commitment, so the
	// only the remote add height should be set during a restore.
	aliceChannel = restoreAndAssertCommitHeights(
		t, aliceChannel, false, 0, 0, 1,
	)

	// Bob receives this commitment signature, and revokes his old state.
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err, "unable to receive commitment")
	bobRevocation, _, _, err := bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to revoke commitment")

	// Now the HTLC is locked into Bob's commitment, a restoration should
	// set only the local commit height, as it is not locked into Alice's
	// yet.
	bobChannel = restoreAndAssertCommitHeights(t, bobChannel, true, 0, 1, 0)

	// Alice receives the revocation, ACKing her pending commitment.
	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err, "unable to receive revocation")

	// However, the HTLC is still not locked into her local commitment, so
	// the local add height should still be 0 after a restoration.
	aliceChannel = restoreAndAssertCommitHeights(
		t, aliceChannel, false, 0, 0, 1,
	)

	// Now let Bob send the commitment signature making the HTLC lock in on
	// Alice's commitment.
	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign commitment")

	// At this stage Bob has a pending remote commitment. Make sure
	// restoring at this stage correctly restores the HTLC add commit
	// heights.
	bobChannel = restoreAndAssertCommitHeights(t, bobChannel, true, 0, 1, 1)

	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err, "unable to receive commitment")
	aliceRevocation, _, _, err := aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to revoke commitment")

	// Now both the local and remote add heights should be properly set.
	aliceChannel = restoreAndAssertCommitHeights(
		t, aliceChannel, false, 0, 1, 1,
	)

	_, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err, "unable to receive revocation")

	// Alice ACKing Bob's pending commitment shouldn't change the heights
	// restored.
	bobChannel = restoreAndAssertCommitHeights(t, bobChannel, true, 0, 1, 1)

	// Send andother HTLC from Alice to Bob, to test whether already
	// existing HTLCs (the HTLC with index 0) keep getting the add heights
	// restored properly.
	htlcAlice, _ = createHTLC(1, htlcAmount)
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlcAlice, nil)

	// Send a new signature from Alice to Bob, making Alice have a pending
	// remote commitment.
	aliceNewCommit, err = aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign commitment")

	// A restoration should keep the add heights iof the first HTLC, and
	// the new HTLC should have a remote add height 2.
	aliceChannel = restoreAndAssertCommitHeights(
		t, aliceChannel, false, 0, 1, 1,
	)
	aliceChannel = restoreAndAssertCommitHeights(
		t, aliceChannel, false, 1, 0, 2,
	)

	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err, "unable to receive commitment")
	bobRevocation, _, _, err = bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to revoke commitment")

	// Since Bob just revoked another commitment, a restoration should
	// increase the add height of the first HTLC to 2, as we only keep the
	// last unrevoked commitment. The new HTLC will also have a local add
	// height of 2.
	bobChannel = restoreAndAssertCommitHeights(t, bobChannel, true, 0, 2, 1)
	bobChannel = restoreAndAssertCommitHeights(t, bobChannel, true, 1, 2, 0)

	// Alice receives the revocation, ACKing her pending commitment for Bob.
	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err, "unable to receive revocation")

	// Alice receiving Bob's revocation should bump both addCommitHeightRemote
	// heights to 2.
	aliceChannel = restoreAndAssertCommitHeights(
		t, aliceChannel, false, 0, 1, 2,
	)
	aliceChannel = restoreAndAssertCommitHeights(
		t, aliceChannel, false, 1, 0, 2,
	)

	// Sign a new state for Alice, making Bob have a pending remote
	// commitment.
	bobNewCommit, err = bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign commitment")

	// The signing of a new commitment for Alice should have given the new
	// HTLC an add height.
	bobChannel = restoreAndAssertCommitHeights(t, bobChannel, true, 0, 2, 1)
	bobChannel = restoreAndAssertCommitHeights(t, bobChannel, true, 1, 2, 2)

	// Alice should receive the commitment and send over a revocation.
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err, "unable to receive commitment")
	aliceRevocation, _, _, err = aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to revoke commitment")

	// Both heights should be 2 and they are on both commitments.
	aliceChannel = restoreAndAssertCommitHeights(
		t, aliceChannel, false, 0, 2, 2,
	)
	aliceChannel = restoreAndAssertCommitHeights(
		t, aliceChannel, false, 1, 2, 2,
	)

	// Bob receives the revocation, which should set both addCommitHeightRemote
	// fields to 2.
	_, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err, "unable to receive revocation")

	bobChannel = restoreAndAssertCommitHeights(t, bobChannel, true, 0, 2, 2)
	bobChannel = restoreAndAssertCommitHeights(t, bobChannel, true, 1, 2, 2)

	// Bob now fails back the htlc that was just locked in.
	err = bobChannel.FailHTLC(0, []byte("failreason"), nil, nil, nil)
	require.NoError(t, err, "unable to cancel HTLC")
	err = aliceChannel.ReceiveFailHTLC(0, []byte("bad"))
	require.NoError(t, err, "unable to recv htlc cancel")

	// Now Bob signs for the fail update.
	bobNewCommit, err = bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign commitment")

	// Bob has a pending commitment for Alice, it shouldn't affect the add
	// commit heights though.
	bobChannel = restoreAndAssertCommitHeights(t, bobChannel, true, 0, 2, 2)
	_ = restoreAndAssertCommitHeights(t, bobChannel, true, 1, 2, 2)

	// Alice receives commitment, sends revocation.
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err, "unable to receive commitment")
	_, _, _, err = aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to revoke commitment")

	aliceChannel = restoreAndAssertCommitHeights(
		t, aliceChannel, false, 0, 3, 2,
	)
	_ = restoreAndAssertCommitHeights(t, aliceChannel, false, 1, 3, 2)
}

// TestForceCloseFailLocalDataLoss tests that we don't allow a force close of a
// channel that's in a non-default state.
func TestForceCloseFailLocalDataLoss(t *testing.T) {
	t.Parallel()

	aliceChannel, _, err := CreateTestChannels(
		t, channeldb.SingleFunderBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// Now that we have our set of channels, we'll modify the channel state
	// to have a non-default channel flag.
	err = aliceChannel.channelState.ApplyChanStatus(
		channeldb.ChanStatusLocalDataLoss,
	)
	require.NoError(t, err, "unable to apply channel state")

	// Due to the change above, if we attempt to force close this
	// channel, we should fail as it isn't safe to force close a
	// channel that isn't in the pure default state.
	_, err = aliceChannel.ForceClose()
	require.ErrorIs(t, err, ErrForceCloseLocalDataLoss)
}

// TestForceCloseBorkedState tests that once we force close a channel, it's
// marked as borked in the database. Additionally, all calls to mutate channel
// state should also fail.
func TestForceCloseBorkedState(t *testing.T) {
	t.Parallel()

	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// Do the commitment dance until Bob sends a revocation so Alice is
	// able to receive the revocation, and then also make a new state
	// herself.
	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign commit")
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err, "unable to receive commitment")
	revokeMsg, _, _, err := bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "unable to revoke bob commitment")
	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign commit")
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err, "unable to receive commitment")

	// Now that we have a new Alice channel, we'll force close once to
	// trigger the update on disk to mark the channel as borked.
	if _, err := aliceChannel.ForceClose(); err != nil {
		t.Fatalf("unable to force close channel: %v", err)
	}

	// Next we'll mark the channel as borked before we proceed.
	err = aliceChannel.channelState.ApplyChanStatus(
		channeldb.ChanStatusBorked,
	)
	require.NoError(t, err, "unable to apply chan status")

	// The on-disk state should indicate that the channel is now borked.
	if !aliceChannel.channelState.HasChanStatus(
		channeldb.ChanStatusBorked,
	) {
		t.Fatalf("chan status not updated as borked")
	}

	// At this point, all channel mutating methods should now fail as they
	// shouldn't be able to proceed if the channel is borked.
	_, _, err = aliceChannel.ReceiveRevocation(revokeMsg)
	if err != channeldb.ErrChanBorked {
		t.Fatalf("advance commitment tail should have failed")
	}

	// We manually advance the commitment tail here since the above
	// ReceiveRevocation call will fail before it's actually advanced.
	aliceChannel.commitChains.Remote.advanceTail()
	_, err = aliceChannel.SignNextCommitment(ctxb)
	if err != channeldb.ErrChanBorked {
		t.Fatalf("sign commitment should have failed: %v", err)
	}
	_, _, _, err = aliceChannel.RevokeCurrentCommitment()
	if err != channeldb.ErrChanBorked {
		t.Fatalf("append remove chain tail should have failed")
	}
}

// TestChannelMaxFeeRate ensures we correctly compute a channel initiator's max
// fee rate based on an allocation and its available balance. When a very low
// fee allocation value is selected the max fee rate is always floored at the
// current fee rate of the channel.
func TestChannelMaxFeeRate(t *testing.T) {
	t.Parallel()

	// propertyTest tests that the validateFeeRate function always passes
	// for the output returned by MaxFeeRate for any valid random inputs
	// fed to MaxFeeRate.
	propertyTest := func(c *LightningChannel) func(alloc maxAlloc) bool {
		return func(ma maxAlloc) bool {
			maxFeeRate, _ := c.MaxFeeRate(float64(ma))
			return c.validateFeeRate(maxFeeRate) == nil
		}
	}

	// Create a non-anchor and an anchor channel setup.
	nonAnchorChannel, _, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	anchorChannel, _, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit|
			channeldb.AnchorOutputsBit|channeldb.ZeroHtlcTxFeeBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// Run the property tests for both channel types.
	err = quick.Check(propertyTest(nonAnchorChannel), nil)
	require.NoError(t, err)

	err = quick.Check(propertyTest(anchorChannel), nil)
	require.NoError(t, err)

	testCases := []struct {
		name               string
		channel            *LightningChannel
		maxFeeAlloc        float64
		expectedFeeAlloc   float64
		expectedMinFeeRate bool
	}{
		{
			name:             "non-anchor-channel high fee alloc",
			channel:          nonAnchorChannel,
			maxFeeAlloc:      1.0,
			expectedFeeAlloc: 1.0,
		},
		{
			name: "non-anchor-channel chan low fee " +
				"alloc",
			channel:          nonAnchorChannel,
			maxFeeAlloc:      1e-3,
			expectedFeeAlloc: 1e-3,
		},
		{
			name:             "anchor-channel high chan fee alloc",
			channel:          anchorChannel,
			maxFeeAlloc:      1.0,
			expectedFeeAlloc: 1.0,
		},
		{
			name:             "anchor-channel low fee alloc",
			channel:          anchorChannel,
			maxFeeAlloc:      1e-3,
			expectedFeeAlloc: 1e-3,
		},
		{
			// The fee rate is capped at the current fee rate if the
			// fee allocation is too low.
			name: "non-anchor-channel current fee rate " +
				"cap",
			channel:            nonAnchorChannel,
			maxFeeAlloc:        1e-6,
			expectedMinFeeRate: true,
		},
		{
			name: "non-anchor-channel current fee rate " +
				"cap",
			channel:            nonAnchorChannel,
			maxFeeAlloc:        1e-8,
			expectedMinFeeRate: true,
		},
		{
			name: "anchor-channel current fee rate " +
				"cap",
			channel:            anchorChannel,
			maxFeeAlloc:        1e-6,
			expectedMinFeeRate: true,
		},
		{
			name: "anchor-channel current fee rate " +
				"cap",
			channel:            anchorChannel,
			maxFeeAlloc:        1e-8,
			expectedMinFeeRate: true,
		},
	}

	for _, testCase := range testCases {
		tc := testCase

		maxFeeRate, feeAllocation := tc.channel.MaxFeeRate(
			tc.maxFeeAlloc,
		)

		currentFeeRate := chainfee.SatPerKWeight(
			tc.channel.channelState.LocalCommitment.FeePerKw,
		)

		// When the fee allocation would push our max fee rate below our
		// current commitment fee rate of the channel we cap the max fee
		// rate at the current fee rate of the channel. There might be
		// some rounding inaccuracies due to the fee rate calculation
		// therefore we accept a relative error of 0.1%.
		if tc.expectedMinFeeRate {
			require.InEpsilonf(
				t, float64(currentFeeRate), float64(maxFeeRate),
				1e-3, "expected max fee rate:%d, got max "+
					"fee rate :%d", currentFeeRate,
				maxFeeRate,
			)
		} else {
			// When the max fee rate is not capped because there
			// is enough balance to allocate funds from we compare
			// the fee allocation rather then the max fee rate so
			// that we can reason more easily about the test values.
			// Because of floating point operations we accept
			// a relative error of 0.1%.
			require.InEpsilonf(
				t, tc.expectedFeeAlloc, feeAllocation, 1e-3,
				"expected fee allocation:%f, got fee "+
					"allocation:%f", tc.expectedFeeAlloc,
				feeAllocation,
			)
		}

		err := tc.channel.validateFeeRate(maxFeeRate)
		require.NoErrorf(t, err, "fee rate validation failed")
	}
}

// TestIdealCommitFeeRate tests that we correctly compute the ideal commitment
// fee of a channel given the current network fee, minimum relay fee, maximum
// fee allocation and whether the channel has anchor outputs.
func TestIdealCommitFeeRate(t *testing.T) {
	t.Parallel()

	// propertyTest tests that the validateFeeRate function always passes
	// for the output returned by IdealCommitFeeRate for any valid random
	// inputs fed to IdealCommitFeeRate.
	propertyTest := func(c *LightningChannel) func(ma maxAlloc,
		netFee, minRelayFee, maxAnchorFee fee) bool {

		return func(ma maxAlloc, netFee, minRelayFee,
			maxAnchorFee fee) bool {

			idealFeeRate := c.IdealCommitFeeRate(
				chainfee.SatPerKWeight(netFee),
				chainfee.SatPerKWeight(minRelayFee),
				chainfee.SatPerKWeight(maxAnchorFee),
				float64(ma),
			)

			return c.validateFeeRate(idealFeeRate) == nil
		}
	}

	// Create a non-anchor channel and an anchor test channel.
	nonAnchorChannel, _, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	if err != nil {
		t.Fatalf("unable to create test channels: %v", err)
	}

	anchorChannel, _, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit|
			channeldb.AnchorOutputsBit|
			channeldb.ZeroHtlcTxFeeBit,
	)
	if err != nil {
		t.Fatalf("unable to create test channels: %v", err)
	}

	// Run the property tests for both channel types (non-anchor and
	// anchor).
	err = quick.Check(propertyTest(nonAnchorChannel), nil)
	if err != nil {
		t.Fatal(err)
	}

	err = quick.Check(propertyTest(anchorChannel), nil)
	if err != nil {
		t.Fatal(err)
	}

	// maxFeeRate is a helper function which calculates the maximum fee rate
	// a channel is allowed to allocate to fees. It does not take a minimum
	// fee rate into account.
	maxFeeRate := func(c *LightningChannel,
		maxFeeAlloc float64) chainfee.SatPerKWeight {

		balance, weight := c.availableBalance(AdditionalHtlc)
		feeRate := c.commitChains.Local.tip().feePerKw
		currentFee := feeRate.FeeForWeight(weight)

		maxBalance := balance.ToSatoshis() + currentFee

		maxFee := float64(maxBalance) * maxFeeAlloc

		maxFeeRate := chainfee.SatPerKWeight(
			maxFee / (float64(weight) / 1000),
		)

		return maxFeeRate
	}

	// currentFeeRate calculates the current fee rate of the channel. The
	// ideal fee rate is floored at the current fee rate of the channel.
	currentFeeRate := func(c *LightningChannel) chainfee.SatPerKWeight {
		return c.commitChains.Local.tip().feePerKw
	}

	// testCase definies the test cases when calculating the ideal fee rate
	// for both channel types (non-anchor and anchor channel).
	type testCase struct {
		name               string
		channel            *LightningChannel
		maxFeeAlloc        float64
		networkFeeRate     chainfee.SatPerKWeight
		minRelayFee        chainfee.SatPerKWeight
		maxAnchorCommitFee chainfee.SatPerKWeight
		expectedFeeRate    chainfee.SatPerKWeight
	}

	nonAnchorCases := []testCase{
		{
			name: "ideal fee rate capped at the max " +
				"available fee rate which is smaller than " +
				"the network fee rate",
			channel:        nonAnchorChannel,
			networkFeeRate: 7e8,
			maxFeeAlloc:    1.0,
			// There is not enough balance to pay the network fee so
			// the maximum available fee rate is expected.
			expectedFeeRate: maxFeeRate(nonAnchorChannel, 1.0),
		},
		{
			name: "enough balance for the ideal network " +
				"fee rate",
			channel:         nonAnchorChannel,
			networkFeeRate:  5e8,
			maxFeeAlloc:     1.0,
			expectedFeeRate: 5e8,
		},
		{
			name: "min relay fee rate is greater than " +
				"the ideal network fee rate",
			channel:        nonAnchorChannel,
			networkFeeRate: 5e8,
			maxFeeAlloc:    1.0,
			minRelayFee:    6e8,
			// The min relay fee rate is used as ideal fee rate
			// because we can afford it and it's greater than the
			// network fee rate.
			expectedFeeRate: 6e8,
		},
		{
			name: "max available fee rate is smaller than the " +
				"min relay fee rate",
			channel:        nonAnchorChannel,
			networkFeeRate: 8e8,
			maxFeeAlloc:    1e-3,
			minRelayFee:    7e8,
			// Using 100% of the available balance (fee alloc) for
			// the fee rate but this is still not enough to pay for
			// the min relay fee rate.
			expectedFeeRate: maxFeeRate(nonAnchorChannel, 1.0),
		},
		{
			name: "current fee rate of the channel is used as a" +
				"fee floor because fee alloc is too small " +
				"(fee ratcheting)",
			channel:        nonAnchorChannel,
			networkFeeRate: 8e8,
			maxFeeAlloc:    1e-7,
			// The fee allocation is too small so we floor the ideal
			// fee rate at the current fee rate of the channel.
			expectedFeeRate: currentFeeRate(anchorChannel),
		},
	}

	anchorCases := []testCase{
		{
			name: "fee rate is capped at the max anchor commit " +
				"fee rate, which is equal to the fee floor",
			channel:            anchorChannel,
			networkFeeRate:     7e8,
			maxFeeAlloc:        0.1,
			maxAnchorCommitFee: chainfee.FeePerKwFloor,
			expectedFeeRate:    chainfee.FeePerKwFloor,
		},
		{
			name: "fee rate capped at the max anchor commit fee " +
				"rate",
			channel:            anchorChannel,
			networkFeeRate:     7e8,
			maxFeeAlloc:        1e-6,
			maxAnchorCommitFee: 700,
			expectedFeeRate:    700,
		},
		{
			name: "fee rate is capped at the max commit anchor" +
				"fee rate",
			channel:            anchorChannel,
			networkFeeRate:     7e8,
			maxFeeAlloc:        1e-3,
			maxAnchorCommitFee: 1e5,
			expectedFeeRate:    1e5,
		},
		{
			name: "min relay fee rate is used when " +
				"the max commit anchor fee rate is smaller",
			channel:            anchorChannel,
			networkFeeRate:     7e8,
			maxFeeAlloc:        1e-4,
			minRelayFee:        4e5,
			maxAnchorCommitFee: 3e5,
			expectedFeeRate:    4e5,
		},
		{
			name: "min relay fee rate is used when " +
				"we can still can pay for it using 100% of " +
				"our balance neglecting the initial fee alloc",
			channel:            anchorChannel,
			networkFeeRate:     7e8,
			maxFeeAlloc:        1e-3,
			minRelayFee:        5e5,
			maxAnchorCommitFee: 3e5,
			expectedFeeRate:    5e5,
		},
		{
			name: "max fee rate using 100% of our balance, " +
				"neglecting the initial fee alloc, but still " +
				"not able to account for the min relay fee " +
				"rate",
			channel:            anchorChannel,
			networkFeeRate:     7e8,
			maxFeeAlloc:        1e-3,
			minRelayFee:        4.5e8,
			maxAnchorCommitFee: 3e5,
			// This is the absolute maximum balance which can be
			// used for the commitment fee.
			expectedFeeRate: maxFeeRate(anchorChannel, 1.0),
		},
		{
			name: "current fee rate of the " +
				"commitment channel is used as the max " +
				"commit anchor fee rate because the fee " +
				"alloc. is too small (fee ratcheting)",
			channel:            anchorChannel,
			networkFeeRate:     7e8,
			maxFeeAlloc:        1e-7,
			maxAnchorCommitFee: 1e6,
			expectedFeeRate:    currentFeeRate(anchorChannel),
		},
	}

	assertIdealFeeRate := func(c *LightningChannel, netFee, minRelay,
		maxAnchorCommit chainfee.SatPerKWeight,
		maxFeeAlloc float64, expectedFeeRate chainfee.SatPerKWeight) {

		feeRate := c.IdealCommitFeeRate(
			netFee, minRelay, maxAnchorCommit, maxFeeAlloc,
		)

		// Due to rounding inaccuracies when calculating the fee rate a
		// relative error of 0.1% is tolerated.
		require.InEpsilonf(
			t, float64(expectedFeeRate), float64(feeRate),
			1e-3, "expected max fee rate:%d, got max "+
				"fee rate :%d", currentFeeRate,
			maxFeeRate,
		)

		if err := c.validateFeeRate(feeRate); err != nil {
			t.Fatalf("fee rate validation failed: %v", err)
		}
	}

	t.Run("non-anchor-channel", func(t *testing.T) {
		for _, testCase := range nonAnchorCases {
			tc := testCase

			assertIdealFeeRate(
				tc.channel, tc.networkFeeRate, tc.minRelayFee,
				tc.maxAnchorCommitFee, tc.maxFeeAlloc,
				tc.expectedFeeRate,
			)
		}
	})

	t.Run("anchor-channel", func(t *testing.T) {
		for _, testCase := range anchorCases {
			tc := testCase

			assertIdealFeeRate(
				tc.channel, tc.networkFeeRate, tc.minRelayFee,
				tc.maxAnchorCommitFee, tc.maxFeeAlloc,
				tc.expectedFeeRate,
			)
		}
	})
}

type maxAlloc float64

// Generate ensures that the random value generated by the testing quick
// package for maxAlloc is always a positive float64 between 0 and 1.
func (maxAlloc) Generate(r *rand.Rand, _ int) reflect.Value {
	ma := maxAlloc(r.Float64())
	return reflect.ValueOf(ma)
}

type fee chainfee.SatPerKWeight

// Generate ensures that the random value generated by the testing quick
// package for a fee is always a positive int64.
func (fee) Generate(r *rand.Rand, _ int) reflect.Value {
	am := fee(r.Int63())
	return reflect.ValueOf(am)
}

// TestChannelFeeRateFloor asserts that valid commitments can be proposed and
// received using chainfee.FeePerKwFloor as the initiator's fee rate.
func TestChannelFeeRateFloor(t *testing.T) {
	t.Parallel()

	alice, bob, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// Set the fee rate to the proposing fee rate floor.
	minFee := chainfee.FeePerKwFloor

	// Alice is the initiator, so only she can propose fee updates.
	if err := alice.UpdateFee(minFee); err != nil {
		t.Fatalf("unable to send fee update")
	}
	if err := bob.ReceiveUpdateFee(minFee); err != nil {
		t.Fatalf("unable to receive fee update")
	}

	// Check that alice can still sign commitments.
	aliceNewCommit, err := alice.SignNextCommitment(ctxb)
	require.NoError(t, err, "alice unable to sign commitment")

	// Check that bob can still receive commitments.
	err = bob.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	if err != nil {
		t.Fatalf("bob unable to process alice's new commitment: %v",
			err)
	}
}

// TestFetchParent tests lookup of an entry's parent in the appropriate log.
func TestFetchParent(t *testing.T) {
	tests := []struct {
		name             string
		whoseCommitChain lntypes.ChannelParty
		whoseUpdateLog   lntypes.ChannelParty
		localEntries     []*paymentDescriptor
		remoteEntries    []*paymentDescriptor

		// parentIndex is the parent index of the entry that we will
		// lookup with fetch parent.
		parentIndex uint64

		// expectErr indicates that we expect fetch parent to fail.
		expectErr bool

		// expectedIndex is the htlc index that we expect the parent
		// to have.
		expectedIndex uint64
	}{
		{
			name:             "not found in remote log",
			localEntries:     nil,
			remoteEntries:    nil,
			whoseCommitChain: lntypes.Remote,
			whoseUpdateLog:   lntypes.Remote,
			parentIndex:      0,
			expectErr:        true,
		},
		{
			name:             "not found in local log",
			localEntries:     nil,
			remoteEntries:    nil,
			whoseCommitChain: lntypes.Local,
			whoseUpdateLog:   lntypes.Local,
			parentIndex:      0,
			expectErr:        true,
		},
		{
			name:         "remote log + chain, remote add height 0",
			localEntries: nil,
			remoteEntries: []*paymentDescriptor{
				// This entry will be added at log index =0.
				{
					HtlcIndex: 1,
					addCommitHeights: lntypes.Dual[uint64]{
						Local:  100,
						Remote: 100,
					},
				},
				// This entry will be added at log index =1, it
				// is the parent entry we are looking for.
				{
					HtlcIndex: 2,
					addCommitHeights: lntypes.Dual[uint64]{
						Local:  100,
						Remote: 0,
					},
				},
			},
			whoseCommitChain: lntypes.Remote,
			whoseUpdateLog:   lntypes.Remote,
			parentIndex:      1,
			expectErr:        true,
		},
		{
			name: "remote log, local chain, local add height 0",
			remoteEntries: []*paymentDescriptor{
				// This entry will be added at log index =0.
				{
					HtlcIndex: 1,
					addCommitHeights: lntypes.Dual[uint64]{
						Local:  100,
						Remote: 100,
					},
				},
				// This entry will be added at log index =1, it
				// is the parent entry we are looking for.
				{
					HtlcIndex: 2,
					addCommitHeights: lntypes.Dual[uint64]{
						Local:  0,
						Remote: 100,
					},
				},
			},
			localEntries:     nil,
			whoseCommitChain: lntypes.Local,
			whoseUpdateLog:   lntypes.Remote,
			parentIndex:      1,
			expectErr:        true,
		},
		{
			name: "local log + chain, local add height 0",
			localEntries: []*paymentDescriptor{
				// This entry will be added at log index =0.
				{
					HtlcIndex: 1,
					addCommitHeights: lntypes.Dual[uint64]{
						Local:  100,
						Remote: 100,
					},
				},
				// This entry will be added at log index =1, it
				// is the parent entry we are looking for.
				{
					HtlcIndex: 2,
					addCommitHeights: lntypes.Dual[uint64]{
						Local:  0,
						Remote: 100,
					},
				},
			},
			remoteEntries:    nil,
			whoseCommitChain: lntypes.Local,
			whoseUpdateLog:   lntypes.Local,
			parentIndex:      1,
			expectErr:        true,
		},

		{
			name: "local log + remote chain, remote add height 0",
			localEntries: []*paymentDescriptor{
				// This entry will be added at log index =0.
				{
					HtlcIndex: 1,
					addCommitHeights: lntypes.Dual[uint64]{
						Local:  100,
						Remote: 100,
					},
				},
				// This entry will be added at log index =1, it
				// is the parent entry we are looking for.
				{
					HtlcIndex: 2,
					addCommitHeights: lntypes.Dual[uint64]{
						Local:  100,
						Remote: 0,
					},
				},
			},
			remoteEntries:    nil,
			whoseCommitChain: lntypes.Remote,
			whoseUpdateLog:   lntypes.Local,
			parentIndex:      1,
			expectErr:        true,
		},
		{
			name:         "remote log found",
			localEntries: nil,
			remoteEntries: []*paymentDescriptor{
				// This entry will be added at log index =0.
				{
					HtlcIndex: 1,
					addCommitHeights: lntypes.Dual[uint64]{
						Local:  100,
						Remote: 0,
					},
				},
				// This entry will be added at log index =1, it
				// is the parent entry we are looking for.
				{
					HtlcIndex: 2,
					addCommitHeights: lntypes.Dual[uint64]{
						Local:  100,
						Remote: 100,
					},
				},
			},
			whoseCommitChain: lntypes.Remote,
			whoseUpdateLog:   lntypes.Remote,
			parentIndex:      1,
			expectErr:        false,
			expectedIndex:    2,
		},
		{
			name: "local log found",
			localEntries: []*paymentDescriptor{
				// This entry will be added at log index =0.
				{
					HtlcIndex: 1,
					addCommitHeights: lntypes.Dual[uint64]{
						Local:  0,
						Remote: 100,
					},
				},
				// This entry will be added at log index =1, it
				// is the parent entry we are looking for.
				{
					HtlcIndex: 2,
					addCommitHeights: lntypes.Dual[uint64]{
						Local:  100,
						Remote: 100,
					},
				},
			},
			remoteEntries:    nil,
			whoseCommitChain: lntypes.Local,
			whoseUpdateLog:   lntypes.Local,
			parentIndex:      1,
			expectErr:        false,
			expectedIndex:    2,
		},
	}

	for _, test := range tests {
		test := test

		t.Run(test.name, func(t *testing.T) {
			// Create a lightning channel with newly initialized
			// local and remote logs.
			lc := LightningChannel{
				updateLogs: lntypes.Dual[*updateLog]{
					Local:  newUpdateLog(0, 0),
					Remote: newUpdateLog(0, 0),
				},
			}

			// Add the local and remote entries to update logs.
			for _, entry := range test.localEntries {
				lc.updateLogs.Local.appendHtlc(entry)
			}
			for _, entry := range test.remoteEntries {
				lc.updateLogs.Remote.appendHtlc(entry)
			}

			parent, err := lc.fetchParent(
				&paymentDescriptor{
					ParentIndex: test.parentIndex,
				},
				test.whoseCommitChain,
				test.whoseUpdateLog,
			)
			gotErr := err != nil
			if test.expectErr != gotErr {
				t.Fatalf("expected error: %v, got: %v, "+
					"error:%v", test.expectErr, gotErr, err)
			}

			// If our lookup failed, we do not need to check parent
			// index.
			if err != nil {
				return
			}

			if parent.HtlcIndex != test.expectedIndex {
				t.Fatalf("expected parent index: %v, got: %v",
					test.parentIndex, parent.HtlcIndex)
			}
		})
	}
}

// TestEvaluateView tests the creation of a htlc view and the opt in mutation of
// send and receive balances. This test does not check htlc mutation on a htlc
// level.
func TestEvaluateView(t *testing.T) {
	const (
		// addHeight is a non-zero height that is used for htlc adds.
		addHeight = 200

		// nextHeight is a constant that we use for the next height in
		// all unit tests.
		nextHeight = 400

		// feePerKw is the fee we start all of our unit tests with.
		feePerKw = 1

		// htlcAddAmount is the amount for htlc adds in tests.
		htlcAddAmount = 15

		// ourFeeUpdateAmt is an amount that we update fees to
		// expressed in msat.
		ourFeeUpdateAmt = 20000

		// ourFeeUpdatePerSat is the fee rate *in satoshis* that we
		// expect if we update to ourFeeUpdateAmt.
		ourFeeUpdatePerSat = chainfee.SatPerKWeight(20)

		// theirFeeUpdateAmt iis an amount that they update fees to
		// expressed in msat.
		theirFeeUpdateAmt = 10000

		// theirFeeUpdatePerSat is the fee rate *in satoshis* that we
		// expect if we update to ourFeeUpdateAmt.
		theirFeeUpdatePerSat = chainfee.SatPerKWeight(10)
	)

	tests := []struct {
		name             string
		ourHtlcs         []*paymentDescriptor
		theirHtlcs       []*paymentDescriptor
		channelInitiator lntypes.ChannelParty
		whoseCommitChain lntypes.ChannelParty
		mutateState      bool

		// ourExpectedHtlcs is the set of our htlcs that we expect in
		// the htlc view once it has been evaluated. We just store
		// htlc index -> bool for brevity, because we only check the
		// presence of the htlc in the returned set.
		ourExpectedHtlcs map[uint64]bool

		// theirExpectedHtlcs is the set of their htlcs that we expect
		// in the htlc view once it has been evaluated. We just store
		// htlc index -> bool for brevity, because we only check the
		// presence of the htlc in the returned set.
		theirExpectedHtlcs map[uint64]bool

		// expectedFee is the fee we expect to be set after evaluating
		// the htlc view.
		expectedFee chainfee.SatPerKWeight

		// expectReceived is the amount we expect the channel to have
		// tracked as our receive total.
		expectReceived lnwire.MilliSatoshi

		// expectSent is the amount we expect the channel to have
		// tracked as our send total.
		expectSent lnwire.MilliSatoshi
	}{
		{
			name:             "our fee update is applied",
			channelInitiator: lntypes.Local,
			whoseCommitChain: lntypes.Local,
			mutateState:      false,
			ourHtlcs: []*paymentDescriptor{
				{
					Amount:    ourFeeUpdateAmt,
					EntryType: FeeUpdate,
				},
			},
			theirHtlcs:         nil,
			expectedFee:        ourFeeUpdatePerSat,
			ourExpectedHtlcs:   nil,
			theirExpectedHtlcs: nil,
			expectReceived:     0,
			expectSent:         0,
		},
		{
			name:             "their fee update is applied",
			channelInitiator: lntypes.Remote,
			whoseCommitChain: lntypes.Local,
			mutateState:      false,
			ourHtlcs:         []*paymentDescriptor{},
			theirHtlcs: []*paymentDescriptor{
				{
					Amount:    theirFeeUpdateAmt,
					EntryType: FeeUpdate,
				},
			},
			expectedFee:        theirFeeUpdatePerSat,
			ourExpectedHtlcs:   nil,
			theirExpectedHtlcs: nil,
			expectReceived:     0,
			expectSent:         0,
		},
		{
			// We expect unresolved htlcs to to remain in the view.
			name:             "htlcs adds without settles",
			whoseCommitChain: lntypes.Local,
			mutateState:      false,
			ourHtlcs: []*paymentDescriptor{
				{
					HtlcIndex: 0,
					Amount:    htlcAddAmount,
					EntryType: Add,
				},
			},
			theirHtlcs: []*paymentDescriptor{
				{
					HtlcIndex: 0,
					Amount:    htlcAddAmount,
					EntryType: Add,
				},
				{
					HtlcIndex: 1,
					Amount:    htlcAddAmount,
					EntryType: Add,
				},
			},
			expectedFee: feePerKw,
			ourExpectedHtlcs: map[uint64]bool{
				0: true,
			},
			theirExpectedHtlcs: map[uint64]bool{
				0: true,
				1: true,
			},
			expectReceived: 0,
			expectSent:     0,
		},
		{
			name:             "our htlc settled, state mutated",
			whoseCommitChain: lntypes.Local,
			mutateState:      true,
			ourHtlcs: []*paymentDescriptor{
				{
					HtlcIndex: 0,
					Amount:    htlcAddAmount,
					EntryType: Add,
					addCommitHeights: lntypes.Dual[uint64]{
						Local: addHeight,
					},
				},
			},
			theirHtlcs: []*paymentDescriptor{
				{
					HtlcIndex: 0,
					Amount:    htlcAddAmount,
					EntryType: Add,
				},
				{
					HtlcIndex: 1,
					Amount:    htlcAddAmount,
					EntryType: Settle,
					// Map their htlc settle update to our
					// htlc add (0).
					ParentIndex: 0,
				},
			},
			expectedFee:      feePerKw,
			ourExpectedHtlcs: nil,
			theirExpectedHtlcs: map[uint64]bool{
				0: true,
			},
			expectReceived: 0,
			expectSent:     htlcAddAmount,
		},
		{
			name:             "our htlc settled, state not mutated",
			whoseCommitChain: lntypes.Local,
			mutateState:      false,
			ourHtlcs: []*paymentDescriptor{
				{
					HtlcIndex: 0,
					Amount:    htlcAddAmount,
					EntryType: Add,
					addCommitHeights: lntypes.Dual[uint64]{
						Local: addHeight,
					},
				},
			},
			theirHtlcs: []*paymentDescriptor{
				{
					HtlcIndex: 0,
					Amount:    htlcAddAmount,
					EntryType: Add,
				},
				{
					HtlcIndex: 1,
					Amount:    htlcAddAmount,
					EntryType: Settle,
					// Map their htlc settle update to our
					// htlc add (0).
					ParentIndex: 0,
				},
			},
			expectedFee:      feePerKw,
			ourExpectedHtlcs: nil,
			theirExpectedHtlcs: map[uint64]bool{
				0: true,
			},
			expectReceived: 0,
			expectSent:     0,
		},
		{
			name:             "their htlc settled, state mutated",
			whoseCommitChain: lntypes.Local,
			mutateState:      true,
			ourHtlcs: []*paymentDescriptor{
				{
					HtlcIndex: 0,
					Amount:    htlcAddAmount,
					EntryType: Add,
				},
				{
					HtlcIndex: 1,
					Amount:    htlcAddAmount,
					EntryType: Settle,
					// Map our htlc settle update to their
					// htlc add (1).
					ParentIndex: 1,
				},
			},
			theirHtlcs: []*paymentDescriptor{
				{
					HtlcIndex: 0,
					Amount:    htlcAddAmount,
					EntryType: Add,
					addCommitHeights: lntypes.Dual[uint64]{
						Local: addHeight,
					},
				},
				{
					HtlcIndex: 1,
					Amount:    htlcAddAmount,
					EntryType: Add,
					addCommitHeights: lntypes.Dual[uint64]{
						Local: addHeight,
					},
				},
			},
			expectedFee: feePerKw,
			ourExpectedHtlcs: map[uint64]bool{
				0: true,
			},
			theirExpectedHtlcs: map[uint64]bool{
				0: true,
			},
			expectReceived: htlcAddAmount,
			expectSent:     0,
		},
		{
			name: "their htlc settled, state not mutated",

			whoseCommitChain: lntypes.Local,
			mutateState:      false,
			ourHtlcs: []*paymentDescriptor{
				{
					HtlcIndex: 0,
					Amount:    htlcAddAmount,
					EntryType: Add,
				},
				{
					HtlcIndex: 1,
					Amount:    htlcAddAmount,
					EntryType: Settle,
					// Map our htlc settle update to their
					// htlc add (0).
					ParentIndex: 0,
				},
			},
			theirHtlcs: []*paymentDescriptor{
				{
					HtlcIndex: 0,
					Amount:    htlcAddAmount,
					EntryType: Add,
					addCommitHeights: lntypes.Dual[uint64]{
						Local: addHeight,
					},
				},
			},
			expectedFee: feePerKw,
			ourExpectedHtlcs: map[uint64]bool{
				0: true,
			},
			theirExpectedHtlcs: nil,
			expectReceived:     0,
			expectSent:         0,
		},
	}

	for _, test := range tests {
		test := test

		t.Run(test.name, func(t *testing.T) {
			isInitiator := test.channelInitiator == lntypes.Local
			lc := LightningChannel{
				channelState: &channeldb.OpenChannel{
					IsInitiator:       isInitiator,
					TotalMSatSent:     0,
					TotalMSatReceived: 0,
				},

				// Create update logs for local and remote.
				updateLogs: lntypes.Dual[*updateLog]{
					Local:  newUpdateLog(0, 0),
					Remote: newUpdateLog(0, 0),
				},
			}

			for _, htlc := range test.ourHtlcs {
				if htlc.EntryType == Add {
					lc.updateLogs.Local.appendHtlc(htlc)
				} else {
					lc.updateLogs.Local.appendUpdate(htlc)
				}
			}

			for _, htlc := range test.theirHtlcs {
				if htlc.EntryType == Add {
					lc.updateLogs.Remote.appendHtlc(htlc)
				} else {
					lc.updateLogs.Remote.appendUpdate(htlc)
				}
			}

			view := &HtlcView{
				Updates: lntypes.Dual[[]*paymentDescriptor]{
					Local:  test.ourHtlcs,
					Remote: test.theirHtlcs,
				},
				FeePerKw: feePerKw,
			}

			// Evaluate the htlc view, mutate as test expects.
			// We do not check the balance deltas in this test
			// because balance modification happens on the htlc
			// processing level.
			result, uncommitted, _, err := lc.evaluateHTLCView(
				view, test.whoseCommitChain, nextHeight,
			)

			if err != nil {
				t.Fatalf("unexpected error: %v", err)
			}

			// TODO(proofofkeags): This block is here because we
			// extracted this code from a previous implementation
			// of evaluateHTLCView, due to a reduced scope of
			// responsibility of that function. Consider removing
			// it from the test altogether.
			if test.mutateState {
				for _, party := range lntypes.BothParties {
					us := uncommitted.GetForParty(party)
					for _, u := range us {
						u.setCommitHeight(
							test.whoseCommitChain,
							nextHeight,
						)
						if test.whoseCommitChain ==
							lntypes.Local &&
							u.EntryType == Settle {

							lc.recordSettlement(
								party, u.Amount,
							)
						}
					}
				}
			}

			if result.FeePerKw != test.expectedFee {
				t.Fatalf("expected fee: %v, got: %v",
					test.expectedFee, result.FeePerKw)
			}

			checkExpectedHtlcs(
				t, result.Updates.Local, test.ourExpectedHtlcs,
			)

			checkExpectedHtlcs(
				t, result.Updates.Remote,
				test.theirExpectedHtlcs,
			)

			if lc.channelState.TotalMSatSent != test.expectSent {
				t.Fatalf("expected sent: %v, got: %v",
					test.expectSent,
					lc.channelState.TotalMSatSent)
			}

			if lc.channelState.TotalMSatReceived !=
				test.expectReceived {

				t.Fatalf("expected received: %v, got: %v",
					test.expectReceived,
					lc.channelState.TotalMSatReceived)
			}
		})
	}
}

// checkExpectedHtlcs checks that a set of htlcs that we have contains all the
// htlcs we expect.
func checkExpectedHtlcs(t *testing.T, actual []*paymentDescriptor,
	expected map[uint64]bool) {

	if len(expected) != len(actual) {
		t.Fatalf("expected: %v htlcs, got: %v",
			len(expected), len(actual))
	}

	for _, htlc := range actual {
		_, ok := expected[htlc.HtlcIndex]
		if !ok {
			t.Fatalf("htlc with index: %v not "+
				"expected in set", htlc.HtlcIndex)
		}
	}
}

// heights represents the heights on a payment descriptor.
type heights struct {
	localAdd     uint64
	localRemove  uint64
	remoteAdd    uint64
	remoteRemove uint64
}

// TestChannelUnsignedAckedFailure tests that unsigned acked updates are
// properly restored after signing for them and disconnecting.
//
// The full state transition of this test is:
//
// Alice                   Bob
//
//	-----add----->
//	-----sig----->
//	<----rev------
//	<----sig------
//	-----rev----->
//	<----fail-----
//	<----sig------
//	-----rev----->
//	-----sig-----X (does not reach Bob! Alice dies!)
//
//	-----sig----->
//	<----rev------
//	<----add------
//	<----sig------
//
// The last sig was rejected with the old behavior of deleting unsigned
// acked updates from the database after signing for them. The current
// behavior of filtering them for deletion upon receiving a revocation
// causes Alice to accept the signature as valid.
func TestChannelUnsignedAckedFailure(t *testing.T) {
	t.Parallel()

	// Create a test channel so that we can test the buggy behavior.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err)

	// First we create an HTLC that Alice sends to Bob.
	htlc, _ := createHTLC(0, lnwire.MilliSatoshi(500000))

	// -----add----->
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)

	// Force a state transition to lock in this add on both commitments.
	// -----sig----->
	// <----rev------
	// <----sig------
	// -----rev----->
	err = ForceStateTransition(aliceChannel, bobChannel)
	require.NoError(t, err)

	// Now Bob should fail the htlc back to Alice.
	// <----fail-----
	err = bobChannel.FailHTLC(0, []byte("failreason"), nil, nil, nil)
	require.NoError(t, err)
	err = aliceChannel.ReceiveFailHTLC(0, []byte("bad"))
	require.NoError(t, err)

	// Bob should send a commitment signature to Alice.
	// <----sig------
	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err)
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err)

	// Alice should reply with a revocation.
	// -----rev----->
	aliceRevocation, _, _, err := aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err)
	_, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err)

	// Alice should sign the next commitment and go down before
	// sending it.
	// -----sig-----X
	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err)

	newAliceChannel, err := NewLightningChannel(
		aliceChannel.Signer, aliceChannel.channelState,
		aliceChannel.sigPool,
	)
	require.NoError(t, err)

	// Bob receives Alice's signature.
	// -----sig----->
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err)

	// Bob revokes his current commitment and sends a revocation
	// to Alice.
	// <----rev------
	bobRevocation, _, _, err := bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err)
	_, _, err = newAliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err)

	// Now Bob sends an HTLC to Alice.
	htlc2, _ := createHTLC(0, lnwire.MilliSatoshi(500000))

	// <----add------
	addAndReceiveHTLC(t, bobChannel, newAliceChannel, htlc2, nil)

	// Bob sends the final signature to Alice and Alice should not
	// reject it, given that we properly restore the unsigned acked
	// updates and therefore our update log is structured correctly.
	bobNewCommit, err = bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err)
	err = newAliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err)
}

// TestChannelLocalUnsignedUpdatesFailure checks that updates from the local
// log are restored if the remote hasn't sent us a signature covering them.
//
// The full state transition is:
//
// Alice                Bob
//
//	<----add-----
//	<----sig-----
//	-----rev---->
//	-----sig---->
//	<----rev-----
//	----fail---->
//	-----sig---->
//	<----rev-----
//	 *reconnect*
//	<----sig-----
//
// Alice should reject the last signature since the settle is not restored
// into the local update log and thus calculates Bob's signature as invalid.
func TestChannelLocalUnsignedUpdatesFailure(t *testing.T) {
	t.Parallel()

	// Create a test channel so that we can test the buggy behavior.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err)

	// First we create an htlc that Bob sends to Alice.
	htlc, _ := createHTLC(0, lnwire.MilliSatoshi(500000))

	// <----add-----
	addAndReceiveHTLC(t, bobChannel, aliceChannel, htlc, nil)

	// Force a state transition to lock in this add on both commitments.
	// <----sig-----
	// -----rev---->
	// -----sig---->
	// <----rev-----
	err = ForceStateTransition(bobChannel, aliceChannel)
	require.NoError(t, err)

	// Now Alice should fail the htlc back to Bob.
	// -----fail--->
	err = aliceChannel.FailHTLC(0, []byte("failreason"), nil, nil, nil)
	require.NoError(t, err)
	err = bobChannel.ReceiveFailHTLC(0, []byte("bad"))
	require.NoError(t, err)

	// Alice should send a commitment signature to Bob.
	// -----sig---->
	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err)
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err)

	// Bob should reply with a revocation and Alice should save the fail as
	// an unsigned local update.
	// <----rev-----
	bobRevocation, _, _, err := bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err)
	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err)

	// Restart Alice and assert that she can receive Bob's next commitment
	// signature.
	// *reconnect*
	newAliceChannel, err := NewLightningChannel(
		aliceChannel.Signer, aliceChannel.channelState,
		aliceChannel.sigPool,
	)
	require.NoError(t, err)

	// Bob sends the final signature and Alice should not reject it.
	// <----sig-----
	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err)
	err = newAliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err)
}

// TestChannelSignedAckRegression tests a previously-regressing state
// transition no longer causes channel desynchronization.
//
// The full state transition of this test is:
//
// Alice                   Bob
//
//	<----add-------
//	<----sig-------
//	-----rev------>
//	-----sig------>
//	<----rev-------
//	----settle---->
//	-----sig------>
//	<----rev-------
//	<----sig-------
//	-----add------>
//	-----sig------>
//	<----rev-------
//	                *restarts*
//	-----rev------>
//	<----sig-------
func TestChannelSignedAckRegression(t *testing.T) {
	t.Parallel()

	// Create test channels to test out this state transition.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err)

	// Create an HTLC that Bob will send to Alice.
	htlc, preimage := createHTLC(0, lnwire.MilliSatoshi(5000000))

	// <----add------
	addAndReceiveHTLC(t, bobChannel, aliceChannel, htlc, nil)

	// Force a state transition to lock in the HTLC.
	// <----sig------
	// -----rev----->
	// -----sig----->
	// <----rev------
	err = ForceStateTransition(bobChannel, aliceChannel)
	require.NoError(t, err)

	// Alice settles the HTLC back to Bob.
	// ----settle--->
	err = aliceChannel.SettleHTLC(preimage, uint64(0), nil, nil, nil)
	require.NoError(t, err)
	err = bobChannel.ReceiveHTLCSettle(preimage, uint64(0))
	require.NoError(t, err)

	// -----sig---->
	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err)
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err)

	// <----rev-----
	bobRevocation, _, _, err := bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err)
	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err)

	// <----sig-----
	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err)
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err)

	// Create an HTLC that Alice will send to Bob.
	htlc2, _ := createHTLC(0, lnwire.MilliSatoshi(5000000))

	// -----add---->
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc2, nil)

	// -----sig---->
	aliceNewCommit, err = aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err)
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err)

	// <----rev-----
	bobRevocation, _, _, err = bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err)
	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err)

	// Restart Bob's channel state here.
	newBobChannel, err := NewLightningChannel(
		bobChannel.Signer, bobChannel.channelState,
		bobChannel.sigPool,
	)
	require.NoError(t, err)

	// -----rev---->
	aliceRevocation, _, _, err := aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err)
	fwdPkg, _, err := newBobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err)

	// Assert that the fwdpkg is not empty.
	require.Equal(t, len(fwdPkg.SettleFails), 1)

	// Bob should no longer fail to sign this commitment due to faulty
	// update logs.
	// <----sig-----
	bobNewCommit, err = newBobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err)

	// Alice should receive the new commitment without hiccups.
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err)
}

// TestMayAddOutgoingHtlc tests MayAddOutgoingHtlc against zero and non-zero
// htlc amounts.
func TestMayAddOutgoingHtlc(t *testing.T) {
	t.Parallel()

	// The default channel created as a part of the test fixture already
	// has a MinHTLC value of zero, so we don't need to do anything here
	// other than create it.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err)

	// The channels start out with a 50/50 balance, so both sides should be
	// able to add an outgoing HTLC with no specific amount added.
	require.NoError(t, aliceChannel.MayAddOutgoingHtlc(0))
	require.NoError(t, bobChannel.MayAddOutgoingHtlc(0))

	chanBal, err := btcutil.NewAmount(testChannelCapacity)
	require.NoError(t, err)

	// Each side should be able to add 1/4 of total channel balance since
	// we're 50/50 split.
	mayAdd := lnwire.MilliSatoshi(chanBal / 4 * 1000)
	require.NoError(t, aliceChannel.MayAddOutgoingHtlc(mayAdd))
	require.NoError(t, bobChannel.MayAddOutgoingHtlc(mayAdd))

	// Both channels should fail if we try to add an amount more than
	// their current balance.
	mayNotAdd := lnwire.MilliSatoshi(chanBal * 1000)
	require.Error(t, aliceChannel.MayAddOutgoingHtlc(mayNotAdd))
	require.Error(t, bobChannel.MayAddOutgoingHtlc(mayNotAdd))

	// Hard set alice's min htlc to zero and test the case where we just
	// fall back to a non-zero value.
	aliceChannel.channelState.LocalChanCfg.MinHTLC = 0
	require.NoError(t, aliceChannel.MayAddOutgoingHtlc(0))
}

// TestIsChannelClean tests that IsChannelClean returns the expected values
// in different channel states.
func TestIsChannelClean(t *testing.T) {
	t.Parallel()

	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.ZeroHtlcTxFeeBit,
	)
	require.NoError(t, err)

	// Channel state should be clean at the start of the test.
	assertCleanOrDirty(true, aliceChannel, bobChannel, t)

	// Assert that neither side considers the channel clean when alice
	// sends an htlc.
	// ---add--->
	htlc, preimage := createHTLC(0, lnwire.MilliSatoshi(5000000))
	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)
	assertCleanOrDirty(false, aliceChannel, bobChannel, t)

	// Assert that the channel remains dirty until the HTLC is completely
	// removed from both commitments.

	// ---sig--->
	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err)
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err)
	assertCleanOrDirty(false, aliceChannel, bobChannel, t)

	// <---rev---
	bobRevocation, _, _, err := bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err)
	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err)
	assertCleanOrDirty(false, aliceChannel, bobChannel, t)

	// <---sig---
	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err)
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err)
	assertCleanOrDirty(false, aliceChannel, bobChannel, t)

	// ---rev--->
	aliceRevocation, _, _, err := aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err)
	_, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err)
	assertCleanOrDirty(false, aliceChannel, bobChannel, t)

	// <--settle--
	err = bobChannel.SettleHTLC(preimage, 0, nil, nil, nil)
	require.NoError(t, err)
	err = aliceChannel.ReceiveHTLCSettle(preimage, 0)
	require.NoError(t, err)
	assertCleanOrDirty(false, aliceChannel, bobChannel, t)

	// <---sig---
	bobNewCommit, err = bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err)
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err)
	assertCleanOrDirty(false, aliceChannel, bobChannel, t)

	// ---rev--->
	aliceRevocation, _, _, err = aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err)
	_, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err)
	assertCleanOrDirty(false, aliceChannel, bobChannel, t)

	// ---sig--->
	aliceNewCommit, err = aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err)
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err)
	assertCleanOrDirty(false, aliceChannel, bobChannel, t)

	// <---rev---
	bobRevocation, _, _, err = bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err)
	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err)
	assertCleanOrDirty(true, aliceChannel, bobChannel, t)

	// Now we check that update_fee is handled and state is dirty until it
	// is completely locked in.
	// ---fee--->
	fee := chainfee.SatPerKWeight(333)
	err = aliceChannel.UpdateFee(fee)
	require.NoError(t, err)
	err = bobChannel.ReceiveUpdateFee(fee)
	require.NoError(t, err)
	assertCleanOrDirty(false, aliceChannel, bobChannel, t)

	// ---sig--->
	aliceNewCommit, err = aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err)
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err)
	assertCleanOrDirty(false, aliceChannel, bobChannel, t)

	// <---rev---
	bobRevocation, _, _, err = bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err)
	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err)
	assertCleanOrDirty(false, aliceChannel, bobChannel, t)

	// <---sig---
	bobNewCommit, err = bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err)
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err)
	assertCleanOrDirty(false, aliceChannel, bobChannel, t)

	// The state should finally be clean after alice sends her revocation.
	// ---rev--->
	aliceRevocation, _, _, err = aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err)
	_, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err)
	assertCleanOrDirty(true, aliceChannel, bobChannel, t)
}

// assertCleanOrDirty is a helper function that asserts that both channels are
// clean if clean is true, and dirty if clean is false.
func assertCleanOrDirty(clean bool, alice, bob *LightningChannel,
	t *testing.T) {

	t.Helper()

	if clean {
		require.True(t, alice.IsChannelClean())
		require.True(t, bob.IsChannelClean())
		return
	}

	require.False(t, alice.IsChannelClean())
	require.False(t, bob.IsChannelClean())
}

// TestChannelGetDustSum tests that we correctly calculate the channel's dust
// sum for the local and remote commitments.
func TestChannelGetDustSum(t *testing.T) {
	t.Run("dust sum tweakless", func(t *testing.T) {
		testGetDustSum(t, channeldb.SingleFunderTweaklessBit)
	})
	t.Run("dust sum anchors zero htlc fee", func(t *testing.T) {
		testGetDustSum(t, channeldb.SingleFunderTweaklessBit|
			channeldb.AnchorOutputsBit|
			channeldb.ZeroHtlcTxFeeBit,
		)
	})
}

func testGetDustSum(t *testing.T, chantype channeldb.ChannelType) {
	t.Parallel()

	// This makes a channel with Alice's dust limit set to 200sats and
	// Bob's dust limit set to 1300sats.
	aliceChannel, bobChannel, err := CreateTestChannels(t, chantype)
	require.NoError(t, err)

	// Use a function closure to assert the dust sum for a passed channel's
	// local and remote commitments match the expected values.
	checkDust := func(c *LightningChannel, expLocal,
		expRemote lnwire.MilliSatoshi) {

		localDustSum := c.GetDustSum(
			lntypes.Local, fn.None[chainfee.SatPerKWeight](),
		)
		require.Equal(t, expLocal, localDustSum)
		remoteDustSum := c.GetDustSum(
			lntypes.Remote, fn.None[chainfee.SatPerKWeight](),
		)
		require.Equal(t, expRemote, remoteDustSum)
	}

	// We'll lower the fee from 6000sats/kWU to 253sats/kWU for our test.
	fee := chainfee.SatPerKWeight(253)
	err = aliceChannel.UpdateFee(fee)
	require.NoError(t, err)
	err = bobChannel.ReceiveUpdateFee(fee)
	require.NoError(t, err)
	err = ForceStateTransition(aliceChannel, bobChannel)
	require.NoError(t, err)

	// Create an HTLC that Bob will send to Alice which is above Alice's
	// dust limit and below Bob's dust limit. This takes into account dust
	// trimming for non-zero-fee channels.
	htlc1Amt := lnwire.MilliSatoshi(700_000)
	htlc1, preimage1 := createHTLC(0, htlc1Amt)

	addAndReceiveHTLC(t, bobChannel, aliceChannel, htlc1, nil)

	// Assert that GetDustSum from Alice's perspective does not consider
	// the HTLC dust on her commitment, but does on Bob's commitment.
	checkDust(aliceChannel, lnwire.MilliSatoshi(0), htlc1Amt)

	// Assert that GetDustSum from Bob's perspective results in the same
	// conditions above holding.
	checkDust(bobChannel, htlc1Amt, lnwire.MilliSatoshi(0))

	// Forcing a state transition to occur should not change the dust sum.
	err = ForceStateTransition(bobChannel, aliceChannel)
	require.NoError(t, err)
	checkDust(aliceChannel, lnwire.MilliSatoshi(0), htlc1Amt)
	checkDust(bobChannel, htlc1Amt, lnwire.MilliSatoshi(0))

	// Settling the HTLC back from Alice to Bob should not change the dust
	// sum because the HTLC is counted until it's removed from the update
	// logs via compactLogs.
	err = aliceChannel.SettleHTLC(preimage1, uint64(0), nil, nil, nil)
	require.NoError(t, err)
	err = bobChannel.ReceiveHTLCSettle(preimage1, uint64(0))
	require.NoError(t, err)
	checkDust(aliceChannel, lnwire.MilliSatoshi(0), htlc1Amt)
	checkDust(bobChannel, htlc1Amt, lnwire.MilliSatoshi(0))

	// Forcing a state transition will remove the HTLC in-memory for Bob
	// since ReceiveRevocation is called which calls compactLogs. Bob
	// should have a zero dust sum at this point. Alice will see Bob as
	// having the original dust sum since compactLogs hasn't been called.
	err = ForceStateTransition(aliceChannel, bobChannel)
	require.NoError(t, err)
	checkDust(aliceChannel, lnwire.MilliSatoshi(0), htlc1Amt)
	checkDust(bobChannel, lnwire.MilliSatoshi(0), lnwire.MilliSatoshi(0))

	// Alice now sends an HTLC of 100sats, which is below both sides' dust
	// limits.
	htlc2Amt := lnwire.MilliSatoshi(100_000)
	htlc2, _ := createHTLC(0, htlc2Amt)

	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc2, nil)

	// Assert that GetDustSum from Alice's perspective includes the new
	// HTLC as dust on both commitments.
	checkDust(aliceChannel, htlc2Amt, htlc1Amt+htlc2Amt)

	// Assert that GetDustSum from Bob's perspective also includes the HTLC
	// on both commitments.
	checkDust(bobChannel, htlc2Amt, htlc2Amt)

	// Alice signs for this HTLC and neither perspective should change.
	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err)
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err)
	checkDust(aliceChannel, htlc2Amt, htlc1Amt+htlc2Amt)
	checkDust(bobChannel, htlc2Amt, htlc2Amt)

	// Bob now sends a revocation for his prior commitment, and this should
	// change Alice's perspective to no longer include the first HTLC as
	// dust.
	bobRevocation, _, _, err := bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err)
	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err)
	checkDust(aliceChannel, htlc2Amt, htlc2Amt)
	checkDust(bobChannel, htlc2Amt, htlc2Amt)

	// The rest of the dance is completed and neither perspective should
	// change.
	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err)
	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err)
	aliceRevocation, _, _, err := aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err)
	_, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
	require.NoError(t, err)
	checkDust(aliceChannel, htlc2Amt, htlc2Amt)
	checkDust(bobChannel, htlc2Amt, htlc2Amt)

	// We'll now assert that if Alice sends an HTLC above her dust limit
	// and then updates the fee of the channel to trigger the trimmed to
	// dust mechanism, Alice will count this HTLC in the dust sum for her
	// commitment in the non-zero-fee case.
	htlc3Amt := lnwire.MilliSatoshi(400_000)
	htlc3, _ := createHTLC(1, htlc3Amt)

	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc3, nil)

	// Assert that this new HTLC is not counted on Alice's local commitment
	// in the dust sum. Bob's commitment should count it.
	checkDust(aliceChannel, htlc2Amt, htlc2Amt+htlc3Amt)
	checkDust(bobChannel, htlc2Amt+htlc3Amt, htlc2Amt)

	// Alice will now send UpdateFee with a large feerate and neither
	// perspective should change.
	fee = chainfee.SatPerKWeight(50_000)
	err = aliceChannel.UpdateFee(fee)
	require.NoError(t, err)
	err = bobChannel.ReceiveUpdateFee(fee)
	require.NoError(t, err)
	checkDust(aliceChannel, htlc2Amt, htlc2Amt+htlc3Amt)
	checkDust(bobChannel, htlc2Amt+htlc3Amt, htlc2Amt)

	// Forcing a state transition should change in the non-zero-fee case.
	err = ForceStateTransition(aliceChannel, bobChannel)
	require.NoError(t, err)
	if chantype.ZeroHtlcTxFee() {
		checkDust(aliceChannel, htlc2Amt, htlc2Amt+htlc3Amt)
		checkDust(bobChannel, htlc2Amt+htlc3Amt, htlc2Amt)
	} else {
		checkDust(aliceChannel, htlc2Amt+htlc3Amt, htlc2Amt+htlc3Amt)
		checkDust(bobChannel, htlc2Amt+htlc3Amt, htlc2Amt+htlc3Amt)
	}
}

// deriveDummyRetributionParams is a helper function that derives a list of
// dummy params to assist retribution creation related tests.
func deriveDummyRetributionParams(chanState *channeldb.OpenChannel) (uint32,
	*CommitmentKeyRing, chainhash.Hash) {

	config := chanState.RemoteChanCfg
	commitHash := chanState.RemoteCommitment.CommitTx.TxHash()
	keyRing := DeriveCommitmentKeys(
		config.RevocationBasePoint.PubKey, lntypes.Remote,
		chanState.ChanType, &chanState.LocalChanCfg,
		&chanState.RemoteChanCfg,
	)
	leaseExpiry := chanState.ThawHeight
	return leaseExpiry, keyRing, commitHash
}

// TestCreateHtlcRetribution checks that `createHtlcRetribution` behaves as
// epxected.
func TestCreateHtlcRetribution(t *testing.T) {
	t.Parallel()

	// Create a dummy private key and an HTLC amount for testing.
	dummyPrivate, _ := btcec.PrivKeyFromBytes([]byte{1})
	testAmt := btcutil.Amount(100)

	// Create a test channel.
	aliceChannel, _, err := CreateTestChannels(
		t, channeldb.ZeroHtlcTxFeeBit,
	)
	require.NoError(t, err)

	// Prepare the params needed to call the function. Note that the values
	// here are not necessary "cryptography-correct", we just use them to
	// construct the htlc retribution.
	leaseExpiry, keyRing, commitHash := deriveDummyRetributionParams(
		aliceChannel.channelState,
	)
	htlc := &channeldb.HTLCEntry{
		Amt: tlv.NewRecordT[tlv.TlvType4](
			tlv.NewBigSizeT(testAmt),
		),
		Incoming:    tlv.NewPrimitiveRecord[tlv.TlvType3](true),
		OutputIndex: tlv.NewPrimitiveRecord[tlv.TlvType2, uint16](1),
	}

	// Create the htlc retribution.
	hr, err := createHtlcRetribution(
		aliceChannel.channelState, keyRing, commitHash,
		dummyPrivate, leaseExpiry, htlc, fn.None[CommitAuxLeaves](),
	)
	// Expect no error.
	require.NoError(t, err)

	// Check the fields have expected values.
	require.EqualValues(t, testAmt, hr.SignDesc.Output.Value)
	require.Equal(t, commitHash, hr.OutPoint.Hash)
	require.EqualValues(t, htlc.OutputIndex.Val, hr.OutPoint.Index)
	require.Equal(t, htlc.Incoming.Val, hr.IsIncoming)
}

// TestCreateBreachRetribution checks that `createBreachRetribution` behaves as
// expected.
func TestCreateBreachRetribution(t *testing.T) {
	t.Parallel()

	// Create dummy values for the test.
	dummyPrivate, _ := btcec.PrivKeyFromBytes([]byte{1})
	testAmt := int64(100)
	ourAmt := int64(1000)
	theirAmt := int64(2000)
	localIndex := uint32(0)
	remoteIndex := uint32(1)
	htlcIndex := uint32(2)

	// Create a dummy breach tx, which has our output located at index 0
	// and theirs at 1.
	spendTx := &wire.MsgTx{
		TxOut: []*wire.TxOut{
			{Value: ourAmt},
			{Value: theirAmt},
			{Value: testAmt},
		},
	}

	// Create a test channel.
	aliceChannel, _, err := CreateTestChannels(
		t, channeldb.ZeroHtlcTxFeeBit,
	)
	require.NoError(t, err)

	// Prepare the params needed to call the function. Note that the values
	// here are not necessary "cryptography-correct", we just use them to
	// construct the retribution.
	leaseExpiry, keyRing, commitHash := deriveDummyRetributionParams(
		aliceChannel.channelState,
	)
	htlc := &channeldb.HTLCEntry{
		Amt: tlv.NewRecordT[tlv.TlvType4](
			tlv.NewBigSizeT(btcutil.Amount(testAmt)),
		),
		Incoming: tlv.NewPrimitiveRecord[tlv.TlvType3](true),
		OutputIndex: tlv.NewPrimitiveRecord[tlv.TlvType2](
			uint16(htlcIndex),
		),
	}

	// Create a dummy revocation log.
	ourAmtMsat := lnwire.MilliSatoshi(ourAmt * 1000)
	theirAmtMsat := lnwire.MilliSatoshi(theirAmt * 1000)
	revokedLog := channeldb.NewRevocationLog(
		uint16(localIndex), uint16(remoteIndex), commitHash,
		fn.Some(ourAmtMsat), fn.Some(theirAmtMsat),
		[]*channeldb.HTLCEntry{htlc}, fn.None[tlv.Blob](),
	)

	// Create a log with an empty local output index.
	revokedLogNoLocal := revokedLog
	revokedLogNoLocal.OurOutputIndex.Val = channeldb.OutputIndexEmpty

	// Create a log with an empty remote output index.
	revokedLogNoRemote := revokedLog
	revokedLogNoRemote.TheirOutputIndex.Val = channeldb.OutputIndexEmpty

	testCases := []struct {
		name             string
		revocationLog    *channeldb.RevocationLog
		expectedErr      error
		expectedOurAmt   int64
		expectedTheirAmt int64
		noSpendTx        bool
	}{
		{
			name: "create retribution successfully " +
				"with spend tx",
			revocationLog:    &revokedLog,
			expectedErr:      nil,
			expectedOurAmt:   ourAmt,
			expectedTheirAmt: theirAmt,
		},
		{
			name: "create retribution successfully " +
				"without spend tx",
			revocationLog:    &revokedLog,
			expectedErr:      nil,
			expectedOurAmt:   ourAmt,
			expectedTheirAmt: theirAmt,
			noSpendTx:        true,
		},
		{
			name: "fail due to our index too big",
			revocationLog: &channeldb.RevocationLog{
				//nolint:lll
				OurOutputIndex: tlv.NewPrimitiveRecord[tlv.TlvType0](
					uint16(htlcIndex + 1),
				),
			},
			expectedErr: ErrOutputIndexOutOfRange,
		},
		{
			name: "fail due to their index too big",
			revocationLog: &channeldb.RevocationLog{
				//nolint:lll
				TheirOutputIndex: tlv.NewPrimitiveRecord[tlv.TlvType1](
					uint16(htlcIndex + 1),
				),
			},
			expectedErr: ErrOutputIndexOutOfRange,
		},
		{
			name: "empty local output index with spend " +
				"tx",
			revocationLog:    &revokedLogNoLocal,
			expectedErr:      nil,
			expectedOurAmt:   0,
			expectedTheirAmt: theirAmt,
		},
		{
			name: "empty local output index without spend " +
				"tx",
			revocationLog:    &revokedLogNoLocal,
			expectedErr:      nil,
			expectedOurAmt:   0,
			expectedTheirAmt: theirAmt,
			noSpendTx:        true,
		},
		{
			name: "empty remote output index with spend " +
				"tx",
			revocationLog:    &revokedLogNoRemote,
			expectedErr:      nil,
			expectedOurAmt:   ourAmt,
			expectedTheirAmt: 0,
		},
		{
			name: "empty remote output index without spend " +
				"tx",
			revocationLog:    &revokedLogNoRemote,
			expectedErr:      nil,
			expectedOurAmt:   ourAmt,
			expectedTheirAmt: 0,
			noSpendTx:        true,
		},
	}

	// assertRetribution is a helper closure that checks a given breach
	// retribution has the expected values on certain fields.
	assertRetribution := func(br *BreachRetribution, our, their int64) {
		chainHash := aliceChannel.channelState.ChainHash
		require.Equal(t, commitHash, br.BreachTxHash)
		require.Equal(t, chainHash, br.ChainHash)

		// Construct local outpoint, we only have the index when the
		// amount is not zero.
		local := wire.OutPoint{
			Hash: commitHash,
		}
		if our != 0 {
			local.Index = localIndex
		}

		// Construct remote outpoint, we only have the index when the
		// amount is not zero.
		remote := wire.OutPoint{
			Hash: commitHash,
		}
		if their != 0 {
			remote.Index = remoteIndex
		}

		require.Equal(t, local, br.LocalOutpoint)
		require.Equal(t, remote, br.RemoteOutpoint)

		for _, hr := range br.HtlcRetributions {
			require.EqualValues(
				t, testAmt, hr.SignDesc.Output.Value,
			)
			require.Equal(t, commitHash, hr.OutPoint.Hash)
			require.EqualValues(t, htlcIndex, hr.OutPoint.Index)
			require.Equal(t, htlc.Incoming.Val, hr.IsIncoming)
		}
	}

	for _, tc := range testCases {
		tc := tc
		t.Run(tc.name, func(t *testing.T) {
			tx := spendTx
			if tc.noSpendTx {
				tx = nil
			}

			br, our, their, err := createBreachRetribution(
				tc.revocationLog, tx,
				aliceChannel.channelState, keyRing,
				dummyPrivate, leaseExpiry,
				fn.None[CommitAuxLeaves](),
			)

			// Check the error if expected.
			if tc.expectedErr != nil {
				require.ErrorIs(t, err, tc.expectedErr)
			} else {
				// Otherwise we expect no error.
				require.NoError(t, err)

				// Check the amounts and the contructed partial
				// retribution are returned as expected.
				require.Equal(t, tc.expectedOurAmt, our)
				require.Equal(t, tc.expectedTheirAmt, their)
				assertRetribution(br, our, their)
			}
		})
	}
}

// TestCreateBreachRetributionLegacy checks that
// `createBreachRetributionLegacy` behaves as expected.
func TestCreateBreachRetributionLegacy(t *testing.T) {
	t.Parallel()

	// Create dummy values for the test.
	dummyPrivate, _ := btcec.PrivKeyFromBytes([]byte{1})

	// Create a test channel.
	aliceChannel, _, err := CreateTestChannels(
		t, channeldb.ZeroHtlcTxFeeBit,
	)
	require.NoError(t, err)

	// Prepare the params needed to call the function. Note that the values
	// here are not necessary "cryptography-correct", we just use them to
	// construct the retribution.
	leaseExpiry, keyRing, _ := deriveDummyRetributionParams(
		aliceChannel.channelState,
	)

	// Use the remote commitment as our revocation log.
	revokedLog := aliceChannel.channelState.RemoteCommitment

	ourOp := revokedLog.CommitTx.TxOut[0]
	theirOp := revokedLog.CommitTx.TxOut[1]

	// Create the dummy scripts.
	ourScript := &WitnessScriptDesc{
		OutputScript: ourOp.PkScript,
	}
	theirScript := &WitnessScriptDesc{
		OutputScript: theirOp.PkScript,
	}

	// Create the breach retribution using the legacy format.
	br, ourAmt, theirAmt, err := createBreachRetributionLegacy(
		&revokedLog, aliceChannel.channelState, keyRing,
		dummyPrivate, ourScript, theirScript, leaseExpiry,
	)
	require.NoError(t, err)

	// Check the commitHash and chainHash.
	commitHash := revokedLog.CommitTx.TxHash()
	chainHash := aliceChannel.channelState.ChainHash
	require.Equal(t, commitHash, br.BreachTxHash)
	require.Equal(t, chainHash, br.ChainHash)

	// Check the outpoints.
	local := wire.OutPoint{
		Hash:  commitHash,
		Index: 0,
	}
	remote := wire.OutPoint{
		Hash:  commitHash,
		Index: 1,
	}
	require.Equal(t, local, br.LocalOutpoint)
	require.Equal(t, remote, br.RemoteOutpoint)

	// Validate the amounts, note that in the legacy format, our amount is
	// not directly the amount found in the to local output. Rather, it's
	// the local output value minus the commit fee and anchor value(if
	// present).
	require.EqualValues(t, revokedLog.LocalBalance.ToSatoshis(), ourAmt)
	require.Equal(t, theirOp.Value, theirAmt)
}

// TestNewBreachRetribution tests that the function `NewBreachRetribution`
// behaves as expected.
func TestNewBreachRetribution(t *testing.T) {
	t.Run("non-anchor", func(t *testing.T) {
		testNewBreachRetribution(t, channeldb.ZeroHtlcTxFeeBit)
	})
	t.Run("anchor", func(t *testing.T) {
		chanType := channeldb.SingleFunderTweaklessBit |
			channeldb.AnchorOutputsBit
		testNewBreachRetribution(t, chanType)
	})
}

// testNewBreachRetribution takes a channel type and tests the function
// `NewBreachRetribution`.
func testNewBreachRetribution(t *testing.T, chanType channeldb.ChannelType) {
	t.Parallel()

	aliceChannel, bobChannel, err := CreateTestChannels(t, chanType)
	require.NoError(t, err)

	breachHeight := uint32(101)
	stateNum := uint64(0)
	chainHash := aliceChannel.channelState.ChainHash
	theirDelay := uint32(aliceChannel.channelState.RemoteChanCfg.CsvDelay)
	breachTx := aliceChannel.channelState.RemoteCommitment.CommitTx

	// Create a breach retribution at height 0, which should give us an
	// error as there are no past delta state saved as revocation logs yet.
	_, err = NewBreachRetribution(
		aliceChannel.channelState, stateNum, breachHeight, breachTx,
		fn.Some[AuxLeafStore](&MockAuxLeafStore{}),
		fn.Some[AuxContractResolver](&MockAuxContractResolver{}),
	)
	require.ErrorIs(t, err, channeldb.ErrNoPastDeltas)

	// We also check that the same error is returned if no breach tx is
	// provided.
	_, err = NewBreachRetribution(
		aliceChannel.channelState, stateNum, breachHeight, nil,
		fn.Some[AuxLeafStore](&MockAuxLeafStore{}),
		fn.Some[AuxContractResolver](&MockAuxContractResolver{}),
	)
	require.ErrorIs(t, err, channeldb.ErrNoPastDeltas)

	// We now force a state transition which will give us a revocation log
	// at height 0.
	txid := aliceChannel.channelState.RemoteCommitment.CommitTx.TxHash()
	err = ForceStateTransition(aliceChannel, bobChannel)
	require.NoError(t, err)

	// assertRetribution is a helper closure that checks a given breach
	// retribution has the expected values on certain fields.
	assertRetribution := func(br *BreachRetribution,
		localIndex, remoteIndex uint32) {

		require.Equal(t, txid, br.BreachTxHash)
		require.Equal(t, chainHash, br.ChainHash)
		require.Equal(t, breachHeight, br.BreachHeight)
		require.Equal(t, stateNum, br.RevokedStateNum)
		require.Equal(t, theirDelay, br.RemoteDelay)

		local := wire.OutPoint{
			Hash:  txid,
			Index: localIndex,
		}
		remote := wire.OutPoint{
			Hash:  txid,
			Index: remoteIndex,
		}

		if chanType.HasAnchors() {
			// For anchor channels, we expect the local delay to be
			// 1 otherwise 0.
			require.EqualValues(t, 1, br.LocalDelay)
		} else {
			require.Zero(t, br.LocalDelay)
		}

		require.Equal(t, local, br.LocalOutpoint)
		require.Equal(t, remote, br.RemoteOutpoint)
	}

	// Create the retribution again and we should expect it to be created
	// successfully.
	br, err := NewBreachRetribution(
		aliceChannel.channelState, stateNum, breachHeight, breachTx,
		fn.Some[AuxLeafStore](&MockAuxLeafStore{}),
		fn.Some[AuxContractResolver](&MockAuxContractResolver{}),
	)
	require.NoError(t, err)

	// Check the retribution is as expected.
	t.Log(spew.Sdump(breachTx))
	assertRetribution(br, 1, 0)

	// Repeat the check but with the breach tx set to nil. This should work
	// since the necessary info should now be found in the revocation log.
	br, err = NewBreachRetribution(
		aliceChannel.channelState, stateNum, breachHeight, nil,
		fn.Some[AuxLeafStore](&MockAuxLeafStore{}),
		fn.Some[AuxContractResolver](&MockAuxContractResolver{}),
	)
	require.NoError(t, err)
	assertRetribution(br, 1, 0)

	// Create the retribution using a stateNum+1 and we should expect an
	// error.
	_, err = NewBreachRetribution(
		aliceChannel.channelState, stateNum+1, breachHeight, breachTx,
		fn.Some[AuxLeafStore](&MockAuxLeafStore{}),
		fn.Some[AuxContractResolver](&MockAuxContractResolver{}),
	)
	require.ErrorIs(t, err, channeldb.ErrLogEntryNotFound)

	// Once again, repeat the check for the case when no breach tx is
	// provided.
	_, err = NewBreachRetribution(
		aliceChannel.channelState, stateNum+1, breachHeight, nil,
		fn.Some[AuxLeafStore](&MockAuxLeafStore{}),
		fn.Some[AuxContractResolver](&MockAuxContractResolver{}),
	)
	require.ErrorIs(t, err, channeldb.ErrLogEntryNotFound)
}

// TestExtractPayDescs asserts that `extractPayDescs` can correctly turn a
// slice of htlcs into two slices of paymentDescriptors.
func TestExtractPayDescs(t *testing.T) {
	t.Parallel()

	// Create a testing LightningChannel.
	lnChan, _, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err)

	// Create two incoming HTLCs.
	incomings := []channeldb.HTLC{
		createRandomHTLC(t, true),
		createRandomHTLC(t, true),
	}

	// Create two outgoing HTLCs.
	outgoings := []channeldb.HTLC{
		createRandomHTLC(t, false),
		createRandomHTLC(t, false),
	}

	// Concatenate incomings and outgoings into a single slice.
	htlcs := []channeldb.HTLC{}
	htlcs = append(htlcs, incomings...)
	htlcs = append(htlcs, outgoings...)

	// Run the method under test.
	//
	// NOTE: we use nil commitment key rings to avoid checking the htlc
	// scripts(`genHtlcScript`) as it should be tested independently.
	incomingPDs, outgoingPDs, err := lnChan.extractPayDescs(
		0, htlcs, lntypes.Dual[*CommitmentKeyRing]{}, lntypes.Local,
		fn.None[CommitAuxLeaves](),
	)
	require.NoError(t, err)

	// Assert the incoming paymentDescriptors are matched.
	for i, pd := range incomingPDs {
		htlc := incomings[i]
		assertPayDescMatchHTLC(t, pd, htlc)
	}

	// Assert the outgoing paymentDescriptors are matched.
	for i, pd := range outgoingPDs {
		htlc := outgoings[i]
		assertPayDescMatchHTLC(t, pd, htlc)
	}
}

// assertPayDescMatchHTLC compares a paymentDescriptor to a channeldb.HTLC and
// asserts that the fields are matched.
func assertPayDescMatchHTLC(t *testing.T, pd paymentDescriptor,
	htlc channeldb.HTLC) {

	require := require.New(t)

	require.EqualValues(htlc.RHash, pd.RHash, "RHash")
	require.Equal(htlc.RefundTimeout, pd.Timeout, "Timeout")
	require.Equal(htlc.Amt, pd.Amount, "Amount")
	require.Equal(htlc.HtlcIndex, pd.HtlcIndex, "HtlcIndex")
	require.Equal(htlc.LogIndex, pd.LogIndex, "LogIndex")
	require.EqualValues(htlc.OnionBlob[:], pd.OnionBlob, "OnionBlob")
}

// createRandomHTLC creates an HTLC that has random value in every field except
// the `Incoming`.
func createRandomHTLC(t *testing.T, incoming bool) channeldb.HTLC {
	var onionBlob [lnwire.OnionPacketSize]byte
	_, err := crand.Read(onionBlob[:])
	require.NoError(t, err)

	var rHash [lntypes.HashSize]byte
	_, err = crand.Read(rHash[:])
	require.NoError(t, err)

	sig := make([]byte, 64)
	_, err = crand.Read(sig)
	require.NoError(t, err)

	randCustomData := make([]byte, 32)
	_, err = crand.Read(randCustomData)
	require.NoError(t, err)

	randCustomType := rand.Intn(255) + lnwire.MinCustomRecordsTlvType

	blinding, err := pubkeyFromHex(
		"0228f2af0abe322403480fb3ee172f7f1601e67d1da6cad40b54c4468d48" +
			"236c39",
	)
	require.NoError(t, err)

	return channeldb.HTLC{
		Signature:     sig,
		RHash:         rHash,
		Amt:           lnwire.MilliSatoshi(rand.Uint64()),
		RefundTimeout: rand.Uint32(),
		OutputIndex:   rand.Int31n(1000),
		Incoming:      incoming,
		OnionBlob:     onionBlob,
		HtlcIndex:     rand.Uint64(),
		LogIndex:      rand.Uint64(),
		BlindingPoint: tlv.SomeRecordT(
			tlv.NewPrimitiveRecord[lnwire.BlindingPointTlvType](
				blinding,
			),
		),
		CustomRecords: map[uint64][]byte{
			uint64(randCustomType): randCustomData,
		},
	}
}

// TestApplyCommitmentFee tests that depending on the buffer type the correct
// commitment fee is calculated which includes the buffer amount which will be
// kept and is not usable hence not considered part of the usable local balance.
func TestApplyCommitmentFee(t *testing.T) {
	var (
		balance = lnwire.NewMSatFromSatoshis(5_000_000)

		// balance used to test the case where the commitment fee
		// including the buffer is greater than the balance.
		balanceBelowReserve = lnwire.NewMSatFromSatoshis(5_000)

		// commitment weight with an additional htlc.
		commitWeight lntypes.WeightUnit = input.
				BaseAnchorCommitmentTxWeight + input.HTLCWeight

		// fee rate of 10 sat/vbyte.
		feePerKw  = chainfee.SatPerKWeight(2500)
		commitFee = lnwire.NewMSatFromSatoshis(
			feePerKw.FeeForWeight(commitWeight),
		)
		additionalHtlc = lnwire.NewMSatFromSatoshis(
			feePerKw.FeeForWeight(input.HTLCWeight),
		)
		feeBuffer = CalcFeeBuffer(feePerKw, commitWeight)
	)

	// Create test channels so that we can use the `applyCommitFee`
	// function.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err)

	testCases := []struct {
		name              string
		channel           *LightningChannel
		buffer            BufferType
		balance           lnwire.MilliSatoshi
		expectedBalance   lnwire.MilliSatoshi
		expectedBufferAmt lnwire.MilliSatoshi
		bufferAmt         lnwire.MilliSatoshi
		expectedErr       error
	}{
		{
			name:              "apply feebuffer local initiator",
			channel:           aliceChannel,
			buffer:            FeeBuffer,
			balance:           balance,
			expectedBalance:   balance - feeBuffer,
			expectedBufferAmt: feeBuffer - commitFee,
		},
		{
			name:        "apply feebuffer remote initiator",
			channel:     bobChannel,
			buffer:      FeeBuffer,
			balance:     balance,
			expectedErr: ErrFeeBufferNotInitiator,
		},
		{
			name:              "apply AdditionalHtlc buffer",
			channel:           aliceChannel,
			buffer:            AdditionalHtlc,
			balance:           balance,
			expectedBalance:   balance - commitFee - additionalHtlc,
			expectedBufferAmt: additionalHtlc,
		},
		{
			name:              "apply NoBuffer",
			channel:           aliceChannel,
			buffer:            NoBuffer,
			balance:           balance,
			expectedBalance:   balance - commitFee,
			expectedBufferAmt: 0,
		},
		{
			name:              "apply FeeBuffer balance negative",
			channel:           aliceChannel,
			buffer:            FeeBuffer,
			balance:           balanceBelowReserve,
			expectedBalance:   balanceBelowReserve,
			expectedErr:       ErrBelowChanReserve,
			expectedBufferAmt: feeBuffer,
		},
	}

	for _, tc := range testCases {
		tc := tc
		t.Run(tc.name, func(t *testing.T) {
			balance, bufferAmt, err := tc.channel.applyCommitFee(
				tc.balance, commitWeight, feePerKw, tc.buffer)

			require.ErrorIs(t, err, tc.expectedErr)
			require.Equal(t, tc.expectedBalance, balance)
			require.Equal(t, tc.expectedBufferAmt, bufferAmt)
		})
	}
}

// TestAsynchronousSendingContraint tests that when both peers add htlcs to
// their commitment asynchronously and the channel opener does not account for
// an additional buffer locally an unusable channel state can be the worst case
// consequence when the channel is locally drained.
// NOTE: This edge case can only be solved at the protocol level because
// currently both parties can add htlcs to their commitments in simultaneously
// which can lead to a situation where the channel opener cannot pay the fees
// for the additional htlc outputs which were added in parallel. A solution for
// this can either be a fee buffer or a new protocol improvement called
// __option_simplified_update__.
//
// The full state transition of this test is:
// The vertical mark in the middle is the connection which separates alice and
// bob. When a line only goes to this mark it means the signal was only added
// to one side of the channel parties.
//
//
// Alice                  		Bob
//			|
// 	-----add------>	|
// 			|<----add-------
//	Add htlcs asynchronously.
// 	<----add------- |
// 			|-----add------>
//	<----sig-------	|---------------
//	-----rev------>	|
//	-----sig------>	|
// 	(Alice fails with ErrBelowChanReserve)

func TestAsynchronousSendingContraint(t *testing.T) {
	t.Parallel()

	// Create test channels to test out this state transition. The channel
	// capactiy is 10 BTC with every side having 5 BTC at start. The fee
	// rate is static and 6000 sats/kw.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err)

	aliceReserve := aliceChannel.channelState.LocalChanCfg.ChanReserve

	capacity := aliceChannel.channelState.Capacity

	// Static fee rate of 6000 sats/kw.
	feePerKw := chainfee.SatPerKWeight(
		aliceChannel.channelState.LocalCommitment.FeePerKw,
	)

	additionalHtlc := feePerKw.FeeForWeight(input.HTLCWeight)
	commitFee := feePerKw.FeeForWeight(input.CommitWeight)

	// We add an htlc to alice commitment with the amount so that everything
	// will be used up and the remote party cannot add another htlc because
	// alice (the opener of the channel) will not be able to afford the
	// additional onchain cost of the htlc output on the commitment tx.
	htlcAmount := capacity/2 - aliceReserve - commitFee - additionalHtlc

	// Create an HTLC that alice will send to Bob which let's alice use up
	// all its local funds.
	// -----add------>|
	htlc1, _ := createHTLC(0, lnwire.NewMSatFromSatoshis(htlcAmount))
	_, err = aliceChannel.addHTLC(htlc1, nil, NoBuffer)
	require.NoError(t, err)

	// Before making bob aware of this new htlc, let bob add an HTLC on the
	// commitment as well. Because bob does not know yet about the htlc
	// alice is going to add to the state his adding will succeed as well.

	// |<----add-------
	// make sure this htlc is non-dust for alice.
	htlcFee := HtlcSuccessFee(channeldb.SingleFunderTweaklessBit, feePerKw)
	// We need to take the remote dustlimit amount, because it the greater
	// one.
	htlcAmt2 := lnwire.NewMSatFromSatoshis(
		aliceChannel.channelState.RemoteChanCfg.DustLimit + htlcFee,
	)
	htlc2, _ := createHTLC(0, htlcAmt2)

	// We could also use AddHTLC here because bob is not the initiator but
	// we stay consistent in this test and use addHTLC instead.
	_, err = bobChannel.addHTLC(htlc2, nil, NoBuffer)
	require.NoError(t, err)

	// Now lets both channel parties know about these new htlcs.
	// <----add-------|
	// 		  |-----add------>
	_, err = aliceChannel.ReceiveHTLC(htlc2)
	require.NoError(t, err)
	_, err = bobChannel.ReceiveHTLC(htlc1)
	require.NoError(t, err)

	// Bob signs the new state for alice, which ONLY has his htlc on it
	// because he only includes acked updates of alice.
	// <----sig-------|---------------
	bobNewCommit, err := bobChannel.SignNextCommitment(ctxb)
	require.NoError(t, err)

	err = aliceChannel.ReceiveNewCommitment(bobNewCommit.CommitSigs)
	require.NoError(t, err)

	// Alice revokes her local commitment which will lead her to include
	// Bobs htlc into the commitment when signing the new state for bob.
	// -----rev------>|
	_, _, _, err = aliceChannel.RevokeCurrentCommitment()
	require.NoError(t, err)

	// Because alice revoked her local commitment she will now include bob's
	// incoming htlc in her commitment sig to bob, but this will dip her
	// local balance below her reserve because she already used everything
	// up when adding her htlc.
	_, err = aliceChannel.SignNextCommitment(ctxb)
	require.ErrorIs(t, err, ErrBelowChanReserve)
}

// TestAsynchronousSendingWithFeeBuffer tests that in case of asynchronous
// adding of htlcs to the channel state a fee buffer will prevent the channel
// from becoming unusable because the channel opener will always keep an
// additional buffer to account either for fee updates or for the asynchronous
// adding of htlcs from both parties.
// The full state transition of this test is:
// The vertical mark in the middle is the connection which separates alice and
// bob. When a line only goes to this mark it means the signal was only added
// to one side of the channel parties.
//
// Alice 		                Bob
// (keeps a feeBuffer)
//
//			|
//	-----add------>	|
//			|<----add-------
//			|
//	<----add------- |
//			|-----add------>
//	---------------	|-----sig------>
//	<----rev-------	|---------------
//	<----sig-------	|---------------
//	---------------	|-----rev------>
// 	alice's htlc is locked-in bob
//	---------------	|-----sig------>
//	<----rev-------	|---------------
// 	bob's htlc is locked-in for alice
//	---------------	|-----fail----->
//	---------------	|-----sig------>
//	<----rev-------	|---------------
//	<----sig-------	|---------------
//	---------------	|-----rev------>
// 	bob's htlc is failed now.
//	use the fee buffer to increase
// 	the fee of the commitment tx:
//	---------------	|----updFee---->
//	---------------	|-----sig------>
//	<----rev-------	|---------------
//	<----sig-------	|---------------
//	---------------	|-----rev------>
// 	let bob add another htlc:
//	<----add------- |<--------------
//	<----sig-------	|---------------
//	---------------	|-----rev------>
//	---------------	|-----sig------>
//	<----rev-------	|---------------

func TestAsynchronousSendingWithFeeBuffer(t *testing.T) {
	t.Parallel()

	// Create test channels to test out this state transition. The channel
	// capactiy is 10 BTC with every side having 5 BTC at start. The fee
	// rate is static and 6000 sats/kw.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err)

	aliceReserve := aliceChannel.channelState.LocalChanCfg.ChanReserve

	capacity := aliceChannel.channelState.Capacity

	// Static fee rate of 6000 sats/kw.
	feePerKw := chainfee.SatPerKWeight(
		aliceChannel.channelState.LocalCommitment.FeePerKw,
	)

	// Calculate the fee buffer for the current commitment tx including
	// the htlc we are going to add to alice's commitment tx.
	feeBuffer := CalcFeeBuffer(
		feePerKw, input.CommitWeight+input.HTLCWeight,
	)

	htlcAmount := capacity/2 - aliceReserve - feeBuffer.ToSatoshis()

	// Create an HTLC that alice will send to bob which uses all the local
	// balance except the fee buffer (including the commitment fee) and the
	// channel reserve.
	htlc1, _ := createHTLC(0, lnwire.NewMSatFromSatoshis(htlcAmount))

	// Add this HTLC only to alice channel for now only including a fee
	// buffer.
	// -----add------>|
	_, err = aliceChannel.AddHTLC(htlc1, nil)
	require.NoError(t, err)

	// Before making bob aware of this new htlc, let bob add an HTLC on the
	// commitment as well.
	// |<----add-------
	// make sure this htlc is non-dust for alice.
	htlcFee := HtlcSuccessFee(channeldb.SingleFunderTweaklessBit, feePerKw)
	htlcAmt2 := lnwire.NewMSatFromSatoshis(
		aliceChannel.channelState.LocalChanCfg.DustLimit + htlcFee,
	)
	htlc2, _ := createHTLC(0, htlcAmt2)
	_, err = bobChannel.AddHTLC(htlc2, nil)
	require.NoError(t, err)

	// Now lets both channel parties know about these new htlcs.
	// 	<----add-------	|
	// 			|-----add------>
	_, err = aliceChannel.ReceiveHTLC(htlc2)
	require.NoError(t, err)
	_, err = bobChannel.ReceiveHTLC(htlc1)
	require.NoError(t, err)

	// Now force the state transisiton. Both sides will succeed although
	// we added htlcs asynchronously because we kept a buffer on alice side
	// We start the state transition with alice.
	// Force a state transition, this will lock-in the htlc of alice.
	// -----sig-----> (includes alice htlc)
	// <----rev------
	// <----sig------ (includes alice and bobs htlc)
	// -----rev-----> (locks in alice's htlc for bob)
	// bob's htlc is still not fully locked in.
	err = ForceStateTransition(aliceChannel, bobChannel)
	require.NoError(t, err)

	// Force a state transition, this will lock-in the htlc of bob.
	// ------sig-----> (includes bob's htlc)
	// <----rev------ (locks in bob's htlc for alice)
	aliceNewCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err)
	err = bobChannel.ReceiveNewCommitment(aliceNewCommit.CommitSigs)
	require.NoError(t, err)

	bobRevocation, _, _, err := bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err)
	_, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
	require.NoError(t, err)

	// Before testing the behavior of the fee buffer, we are going to fail
	// back bob's htlc so that we only have 1 htlc on the commitment tx
	// (alice htlc to bob) this makes it possible to exactly increase the
	// fee of the commitment by 100%.
	//	---------------	|-----fail----->
	//	---------------	|-----sig------>
	//	<----rev-------	|---------------
	//	<----sig-------	|---------------
	//	---------------	|-----rev------>
	err = aliceChannel.FailHTLC(0, []byte{}, nil, nil, nil)
	require.NoError(t, err)

	err = bobChannel.ReceiveFailHTLC(0, []byte{})
	require.NoError(t, err)

	err = ForceStateTransition(aliceChannel, bobChannel)
	require.NoError(t, err)

	// Use the fee buffer to react to a potential fee rate increase and
	// update the fee rate by 100%.
	//	---------------	|----updFee---->
	//	---------------	|-----sig------>
	//	<----rev-------	|---------------
	//	<----sig-------	|---------------
	//	---------------	|-----rev------>
	err = aliceChannel.UpdateFee(feePerKw * 2)
	require.NoError(t, err)

	err = bobChannel.ReceiveUpdateFee(feePerKw * 2)
	require.NoError(t, err)

	err = ForceStateTransition(aliceChannel, bobChannel)
	require.NoError(t, err)

	// Now let bob add an htlc to the commitment tx and make sure that
	// despite the fee update bob can still add an htlc and alice still
	// reserved funds for an additional htlc output on the commitment tx.
	//	<----add------- |<--------------
	//	<----sig-------	|---------------
	//	---------------	|-----rev------>
	//	---------------	|-----sig------>
	//	<----rev-------	|---------------
	// Update the non-dust amount because we updated the fee by 100%.
	htlcFee = HtlcSuccessFee(channeldb.SingleFunderTweaklessBit, feePerKw*2)
	htlcAmt3 := lnwire.NewMSatFromSatoshis(
		aliceChannel.channelState.LocalChanCfg.DustLimit + htlcFee,
	)
	htlc3, _ := createHTLC(1, htlcAmt3)
	addAndReceiveHTLC(t, bobChannel, aliceChannel, htlc3, nil)

	err = ForceStateTransition(bobChannel, aliceChannel)
	require.NoError(t, err)

	// Adding an HTLC from Alice side should not be possible because
	// all funds are used up, even dust amounts.
	htlc4, _ := createHTLC(2, 100)
	// First try adding this htlc which should fail because the FeeBuffer
	// cannot be kept while sending this HTLC.
	_, err = aliceChannel.AddHTLC(htlc4, nil)
	require.ErrorIs(t, err, ErrBelowChanReserve)
	// Even without enforcing the FeeBuffer we used all of our usable funds
	// on this channel and cannot even add a dust-htlc.
	_, err = aliceChannel.addHTLC(htlc4, nil, NoBuffer)
	require.ErrorIs(t, err, ErrBelowChanReserve)

	// All of alice's balance is used up in fees and htlcs so the local
	// balance equals exactly the local reserve.
	require.Equal(t, aliceChannel.channelState.LocalCommitment.LocalBalance,
		lnwire.NewMSatFromSatoshis(aliceReserve))
}

// TestEnforceFeeBuffer tests that in case the channel initiator does NOT have
// enough local balance to pay for the FeeBuffer, adding new HTLCs by the
// initiator will fail. Receiving HTLCs will still work because no FeeBuffer is
// enforced when receiving HTLCs.
//
// The full state transition of this test is:
// The vertical mark in the middle is the connection which separates alice and
// bob. When a line only goes to this mark it means the signal was only added
// to one side of the channel parties.
//
// Alice 		                Bob
// (keeps a feeBuffer)
//
//	--------------- |-----add------>
//	---------------	|-----sig------>
//	<----rev-------	|---------------
//	<----sig-------	|---------------
//	---------------	|-----rev------>
//	alice sends all usable funds to bob
//	<----add------- |---------------
//	<----sig-------	|---------------
//	---------------	|-----rev------>
//	---------------	|-----sig------>
//	<----rev-------	|---------------
//	bob adds an HTLC to the channel
//	-----add------> |
//	adding another HTLC fails because
//	the FeeBuffer cannot be paid.
//	<----add------- |<--------------
//	<----sig-------	|---------------
//	---------------	|-----rev------>
//	---------------	|-----sig------>
//	<----rev-------	|---------------
//	bob adds another HTLC to the channel,
//	alice can still pay the fee for the
//	new commitment tx.
func TestEnforceFeeBuffer(t *testing.T) {
	t.Parallel()

	// Create test channels to test out this state transition. The channel
	// capactiy is 10 BTC with every side having 5 BTC at start. The fee
	// rate is static and 6000 sats/kw.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err)

	aliceReserve := aliceChannel.channelState.LocalChanCfg.ChanReserve

	capacity := aliceChannel.channelState.Capacity

	// Static fee rate of 6000 sats/kw.
	feePerKw := chainfee.SatPerKWeight(
		aliceChannel.channelState.LocalCommitment.FeePerKw,
	)

	// Commitment Fee of the channel state (with  1 pending htlc).
	commitFee := feePerKw.FeeForWeight(
		input.CommitWeight + input.HTLCWeight,
	)
	commitFeeMsat := lnwire.NewMSatFromSatoshis(commitFee)

	// Calculate the FeeBuffer for the current commitment tx (non-anchor)
	// including the htlc alice is going to add to the commitment tx.
	feeBuffer := CalcFeeBuffer(
		feePerKw, input.CommitWeight+input.HTLCWeight,
	)

	// The bufferAmt is the FeeBuffer excluding the commitment fee.
	bufferAmt := feeBuffer - commitFeeMsat

	htlcAmt1 := capacity/2 - aliceReserve - feeBuffer.ToSatoshis()

	// Create an HTLC that alice will send to bob which uses all the local
	// balance except the fee buffer (including the commitment fee) and the
	// channel reserve.
	//	--------------- |-----add------>
	//	---------------	|-----sig------>
	//	<----rev-------	|---------------
	//	<----sig-------	|---------------
	//	---------------	|-----rev------>
	htlc1, _ := createHTLC(0, lnwire.NewMSatFromSatoshis(htlcAmt1))

	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc1, nil)

	err = ForceStateTransition(aliceChannel, bobChannel)
	require.NoError(t, err)

	// Now bob sends a 1 btc htlc to alice.
	//	<----add------- |---------------
	//	<----sig-------	|---------------
	//	---------------	|-----rev------>
	//	---------------	|-----sig------>
	//	<----rev-------	|---------------
	htlcAmt2 := lnwire.NewMSatFromSatoshis(btcutil.SatoshiPerBitcent)
	htlc2, _ := createHTLC(0, htlcAmt2)

	addAndReceiveHTLC(t, bobChannel, aliceChannel, htlc2, nil)

	err = ForceStateTransition(bobChannel, aliceChannel)
	require.NoError(t, err)

	// Alice has the buffer amount left trying to send this amount will
	// fail.
	htlc3, _ := createHTLC(1, bufferAmt)

	_, err = aliceChannel.AddHTLC(htlc3, nil)
	require.ErrorIs(t, err, ErrBelowChanReserve)

	// Now bob sends another 1 btc htlc to alice.
	//	<----add------- |---------------
	//	<----sig-------	|---------------
	//	---------------	|-----rev------>
	//	---------------	|-----sig------>
	//	<----rev-------	|---------------
	htlc4, _ := createHTLC(1, htlcAmt2)

	addAndReceiveHTLC(t, bobChannel, aliceChannel, htlc4, nil)

	err = ForceStateTransition(bobChannel, aliceChannel)
	require.NoError(t, err)

	// Check that alice has the expected local balance left.
	aliceReserveMsat := lnwire.NewMSatFromSatoshis(aliceReserve)

	// The bufferAmt has to pay for the 2 additional incoming htlcs added
	// by bob.
	feeHTLC := feePerKw.FeeForWeight(input.HTLCWeight)
	feeHTLCMsat := lnwire.NewMSatFromSatoshis(feeHTLC)

	aliceBalance := aliceReserveMsat + bufferAmt - 2*feeHTLCMsat
	expectedAmt := aliceChannel.channelState.LocalCommitment.LocalBalance

	require.Equal(t, aliceBalance, expectedAmt)
}

// TestBlindingPointPersistence tests persistence of blinding points attached
// to htlcs across restarts.
func TestBlindingPointPersistence(t *testing.T) {
	// Create a test channel which will be used for the duration of this
	// test. The channel will be funded evenly with Alice having 5 BTC,
	// and Bob having 5 BTC.
	aliceChannel, bobChannel, err := CreateTestChannels(
		t, channeldb.SingleFunderTweaklessBit,
	)
	require.NoError(t, err, "unable to create test channels")

	// Send a HTLC from Alice to Bob that has a blinding point populated.
	htlc, _ := createHTLC(0, 100_000_000)
	blinding, err := pubkeyFromHex(
		"0228f2af0abe322403480fb3ee172f7f1601e67d1da6cad40b54c4468d48236c39", //nolint:lll
	)
	require.NoError(t, err)
	htlc.BlindingPoint = tlv.SomeRecordT(
		tlv.NewPrimitiveRecord[lnwire.BlindingPointTlvType](blinding),
	)

	addAndReceiveHTLC(t, aliceChannel, bobChannel, htlc, nil)

	// Now, Alice will send a new commitment to Bob, which will persist our
	// pending HTLC to disk.
	aliceCommit, err := aliceChannel.SignNextCommitment(ctxb)
	require.NoError(t, err, "unable to sign commitment")

	// Restart alice to force fetching state from disk.
	aliceChannel, err = restartChannel(aliceChannel)
	require.NoError(t, err, "unable to restart alice")

	// Assert that the blinding point is restored from disk.
	remoteCommit := aliceChannel.commitChains.Remote.tip()
	require.Len(t, remoteCommit.outgoingHTLCs, 1)
	require.Equal(t, blinding,
		remoteCommit.outgoingHTLCs[0].BlindingPoint.UnwrapOrFailV(t))

	// Next, update bob's commitment and assert that we can still retrieve
	// his incoming blinding point after restart.
	err = bobChannel.ReceiveNewCommitment(aliceCommit.CommitSigs)
	require.NoError(t, err, "bob unable to receive new commitment")

	_, _, _, err = bobChannel.RevokeCurrentCommitment()
	require.NoError(t, err, "bob unable to revoke current commitment")

	bobChannel, err = restartChannel(bobChannel)
	require.NoError(t, err, "unable to restart bob's channel")

	// Assert that Bob is able to recover the blinding point from disk.
	bobCommit := bobChannel.commitChains.Local.tip()
	require.Len(t, bobCommit.incomingHTLCs, 1)
	require.Equal(t, blinding,
		bobCommit.incomingHTLCs[0].BlindingPoint.UnwrapOrFailV(t))
}

// TestCreateCooperativeCloseTx tests that the cooperative close transaction is
// properly created based on the standard and also optional parameters.
func TestCreateCooperativeCloseTx(t *testing.T) {
	t.Parallel()

	fundingTxIn := &wire.TxIn{}

	localDust := btcutil.Amount(400)
	remoteDust := btcutil.Amount(400)

	localScript := []byte{0}
	localExtraScript := []byte{2}

	remoteScript := []byte{1}
	remoteExtraScript := []byte{3}

	tests := []struct {
		name string

		enableRBF bool

		localBalance  btcutil.Amount
		remoteBalance btcutil.Amount

		extraCloseOutputs []CloseOutput

		expectedTx *wire.MsgTx
	}{
		{
			name:          "no dust, no extra outputs",
			localBalance:  1_000,
			remoteBalance: 1_000,
			expectedTx: &wire.MsgTx{
				TxIn: []*wire.TxIn{
					fundingTxIn,
				},
				Version: 2,
				TxOut: []*wire.TxOut{
					{
						Value:    1_000,
						PkScript: localScript,
					},
					{
						Value:    1_000,
						PkScript: remoteScript,
					},
				},
			},
		},
		{
			name:          "local dust, no extra outputs",
			localBalance:  100,
			remoteBalance: 1_000,
			expectedTx: &wire.MsgTx{
				TxIn: []*wire.TxIn{
					fundingTxIn,
				},
				Version: 2,
				TxOut: []*wire.TxOut{
					{
						Value:    1_000,
						PkScript: remoteScript,
					},
				},
			},
		},
		{
			name:          "remote dust, no extra outputs",
			localBalance:  1_000,
			remoteBalance: 100,
			expectedTx: &wire.MsgTx{
				TxIn: []*wire.TxIn{
					fundingTxIn,
				},
				Version: 2,
				TxOut: []*wire.TxOut{
					{
						Value:    1_000,
						PkScript: localScript,
					},
				},
			},
		},
		{
			name:          "no dust, local extra output",
			localBalance:  10_000,
			remoteBalance: 10_000,
			extraCloseOutputs: []CloseOutput{
				{
					TxOut: wire.TxOut{
						Value:    1_000,
						PkScript: localExtraScript,
					},
					IsLocal: true,
				},
			},
			expectedTx: &wire.MsgTx{
				TxIn: []*wire.TxIn{
					fundingTxIn,
				},
				Version: 2,
				TxOut: []*wire.TxOut{
					{
						Value:    10_000,
						PkScript: remoteScript,
					},
					{
						Value:    9_000,
						PkScript: localScript,
					},
					{
						Value:    1_000,
						PkScript: localExtraScript,
					},
				},
			},
		},
		{
			name:          "no dust, remote extra output",
			localBalance:  10_000,
			remoteBalance: 10_000,
			extraCloseOutputs: []CloseOutput{
				{
					TxOut: wire.TxOut{
						Value:    1_000,
						PkScript: remoteExtraScript,
					},
					IsLocal: false,
				},
			},
			expectedTx: &wire.MsgTx{
				TxIn: []*wire.TxIn{
					fundingTxIn,
				},
				Version: 2,
				TxOut: []*wire.TxOut{
					{
						Value:    10_000,
						PkScript: localScript,
					},
					{
						Value:    9_000,
						PkScript: remoteScript,
					},
					{
						Value:    1_000,
						PkScript: remoteExtraScript,
					},
				},
			},
		},
		{
			name:          "no dust, local+remote extra output",
			localBalance:  10_000,
			remoteBalance: 10_000,
			extraCloseOutputs: []CloseOutput{
				{
					TxOut: wire.TxOut{
						Value:    1_000,
						PkScript: remoteExtraScript,
					},
					IsLocal: false,
				},
				{
					TxOut: wire.TxOut{
						Value:    1_000,
						PkScript: localExtraScript,
					},
					IsLocal: true,
				},
			},
			expectedTx: &wire.MsgTx{
				TxIn: []*wire.TxIn{
					fundingTxIn,
				},
				Version: 2,
				TxOut: []*wire.TxOut{
					{
						Value:    9_000,
						PkScript: localScript,
					},
					{
						Value:    9_000,
						PkScript: remoteScript,
					},
					{
						Value:    1_000,
						PkScript: remoteExtraScript,
					},
					{
						Value:    1_000,
						PkScript: localExtraScript,
					},
				},
			},
		},
		{
			name: "no dust, local+remote extra output, " +
				"remote can't afford",
			localBalance:  10_000,
			remoteBalance: 1_000,
			extraCloseOutputs: []CloseOutput{
				{
					TxOut: wire.TxOut{
						Value:    1_000,
						PkScript: remoteExtraScript,
					},
					IsLocal: false,
				},
				{
					TxOut: wire.TxOut{
						Value:    1_000,
						PkScript: localExtraScript,
					},
					IsLocal: true,
				},
			},
			expectedTx: &wire.MsgTx{
				TxIn: []*wire.TxIn{
					fundingTxIn,
				},
				Version: 2,
				TxOut: []*wire.TxOut{
					{
						Value:    9_000,
						PkScript: localScript,
					},
					{
						Value:    1_000,
						PkScript: remoteExtraScript,
					},
					{
						Value:    1_000,
						PkScript: localExtraScript,
					},
				},
			},
		},
		{
			name: "no dust, local+remote extra output, " +
				"local can't afford",
			localBalance:  1_000,
			remoteBalance: 10_000,
			extraCloseOutputs: []CloseOutput{
				{
					TxOut: wire.TxOut{
						Value:    1_000,
						PkScript: remoteExtraScript,
					},
					IsLocal: false,
				},
				{
					TxOut: wire.TxOut{
						Value:    1_000,
						PkScript: localExtraScript,
					},
					IsLocal: true,
				},
			},
			expectedTx: &wire.MsgTx{
				TxIn: []*wire.TxIn{
					fundingTxIn,
				},
				Version: 2,
				TxOut: []*wire.TxOut{
					{
						Value:    9_000,
						PkScript: remoteScript,
					},
					{
						Value:    1_000,
						PkScript: remoteExtraScript,
					},
					{
						Value:    1_000,
						PkScript: localExtraScript,
					},
				},
			},
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			var opts []CloseTxOpt
			if test.extraCloseOutputs != nil {
				opts = append(
					opts,
					WithExtraTxCloseOutputs(
						test.extraCloseOutputs,
					),
				)
			}

			closeTx, err := CreateCooperativeCloseTx(
				*fundingTxIn, localDust, remoteDust,
				test.localBalance, test.remoteBalance,
				localScript, remoteScript, opts...,
			)
			require.NoError(t, err)

			txsort.InPlaceSort(test.expectedTx)

			require.Equal(
				t, test.expectedTx, closeTx,
				"expected %v, got %v",
				spew.Sdump(test.expectedTx),
				spew.Sdump(closeTx),
			)
		})
	}
}