sweep: rename fee() to feeWithParent() for clarity

To make sure the caller has a better idea about what this method is
doing.

sweep/tx_input_set.go

@@ -222,7 +222,7 @@ func (t *txInputSet) enoughInput() bool {
 	// We did not have enough input for a change output. Check if we have
 	// enough input to pay the fees for a transaction with no change
 	// output.
-	fee := t.weightEstimate(false).fee()
+	fee := t.weightEstimate(false).feeWithParent()
 	if t.inputTotal < t.requiredOutput+fee {
 		return false
 	}
@@ -289,7 +289,7 @@ func (t *txInputSet) addToState(inp input.Input,
 	newSet.inputTotal += value
 
 	// Recalculate the tx fee.
-	fee := newSet.weightEstimate(true).fee()
+	fee := newSet.weightEstimate(true).feeWithParent()
 
 	// Calculate the new output value.
 	if reqOut != nil {

sweep/tx_input_set_test.go

@@ -35,7 +35,7 @@ func TestTxInputSet(t *testing.T) {
 		t.Fatal("expected add of positively yielding input to succeed")
 	}
 
-	fee := set.weightEstimate(true).fee()
+	fee := set.weightEstimate(true).feeWithParent()
 	require.Equal(t, btcutil.Amount(487), fee)
 
 	// The tx output should now be 700-487 = 213 sats. The dust limit isn't
@@ -164,13 +164,13 @@ func TestTxInputSetRequiredOutput(t *testing.T) {
 	require.True(t, set.add(inp, constraintsRegular), "failed adding input")
 
 	// The fee needed to pay for this input and output should be 439 sats.
-	fee := set.weightEstimate(false).fee()
+	fee := set.weightEstimate(false).feeWithParent()
 	require.Equal(t, btcutil.Amount(439), fee)
 
 	// Since the tx set currently pays no fees, we expect the current
 	// change to actually be negative, since this is what it would cost us
 	// in fees to add a change output.
-	feeWithChange := set.weightEstimate(true).fee()
+	feeWithChange := set.weightEstimate(true).feeWithParent()
 	if set.changeOutput != -feeWithChange {
 		t.Fatalf("expected negative change of %v, had %v",
 			-feeWithChange, set.changeOutput)
@@ -188,9 +188,10 @@ func TestTxInputSetRequiredOutput(t *testing.T) {
 	// Now we add a an input that is large enough to pay the fee for the
 	// transaction without a change output, but not large enough to afford
 	// adding a change output.
-	extraInput1 := weight.fee() + 100
+	extraInput1 := weight.feeWithParent() + 100
-	require.True(t, set.add(createP2WKHInput(extraInput1), constraintsRegular),
+	require.True(t, set.add(
-		"expected add of positively yielding input to succeed")
+		createP2WKHInput(extraInput1), constraintsRegular,
+	), "expected add of positively yielding input to succeed")
 
 	// The change should be negative, since we would have to add a change
 	// output, which we cannot yet afford.
@@ -208,10 +209,12 @@ func TestTxInputSetRequiredOutput(t *testing.T) {
 	require.NoError(t, weight.add(dummyInput))
 
 	// We add what is left to reach this value.
-	extraInput2 := weight.fee() - extraInput1 + 100
+	extraInput2 := weight.feeWithParent() - extraInput1 + 100
 
 	// Add this input, which should result in the change now being 100 sats.
-	require.True(t, set.add(createP2WKHInput(extraInput2), constraintsRegular))
+	require.True(t, set.add(
+		createP2WKHInput(extraInput2), constraintsRegular,
+	))
 
 	// The change should be 100, since this is what is left after paying
 	// fees in case of a change output.
@@ -232,7 +235,7 @@ func TestTxInputSetRequiredOutput(t *testing.T) {
 
 	// We expect the change to everything that is left after paying the tx
 	// fee.
-	extraInput3 := weight.fee() - extraInput1 - extraInput2 + 1000
+	extraInput3 := weight.feeWithParent() - extraInput1 - extraInput2 + 1000
 	require.True(t, set.add(createP2WKHInput(extraInput3), constraintsRegular))
 
 	change = set.changeOutput

sweep/txgenerator.go

@@ -44,7 +44,7 @@ func createSweepTx(inputs []input.Input, outputs []*wire.TxOut,
 		return nil, 0, err
 	}
 
-	txFee := estimator.fee()
+	txFee := estimator.feeWithParent()
 
 	var (
 		// Create the sweep transaction that we will be building. We

sweep/weight_estimator.go

@@ -106,9 +106,9 @@ func (w *weightEstimator) weight() int {
 	return w.estimator.Weight()
 }
 
-// fee returns the tx fee to use for the aggregated inputs and outputs, taking
+// feeWithParent returns the tx fee to use for the aggregated inputs and
-// into account unconfirmed parent transactions (cpfp).
+// outputs, taking into account unconfirmed parent transactions (cpfp).
-func (w *weightEstimator) fee() btcutil.Amount {
+func (w *weightEstimator) feeWithParent() btcutil.Amount {
 	// Calculate fee and weight for just this tx.
 	childWeight := int64(w.estimator.Weight())
 

sweep/weight_estimator_test.go

@@ -30,7 +30,8 @@ func TestWeightEstimator(t *testing.T) {
 	// The expectations is that this input is added.
 	const expectedWeight1 = 322
 	require.Equal(t, expectedWeight1, w.weight())
-	require.Equal(t, testFeeRate.FeeForWeight(expectedWeight1), w.fee())
+	require.Equal(t, testFeeRate.FeeForWeight(expectedWeight1),
+		w.feeWithParent())
 
 	// Define a parent transaction that pays a fee of 30000 sat/kw.
 	parentTxHighFee := &input.TxInfo{
@@ -51,7 +52,8 @@ func TestWeightEstimator(t *testing.T) {
 	// rate than the child. We expect no additional fee on the child.
 	const expectedWeight2 = expectedWeight1 + 280
 	require.Equal(t, expectedWeight2, w.weight())
-	require.Equal(t, testFeeRate.FeeForWeight(expectedWeight2), w.fee())
+	require.Equal(t, testFeeRate.FeeForWeight(expectedWeight2),
+		w.feeWithParent())
 
 	// Define a parent transaction that pays a fee of 10000 sat/kw.
 	parentTxLowFee := &input.TxInfo{
@@ -78,7 +80,7 @@ func TestWeightEstimator(t *testing.T) {
 		expectedWeight3+parentTxLowFee.Weight,
 	) - parentTxLowFee.Fee
 
-	require.Equal(t, expectedFee, w.fee())
+	require.Equal(t, expectedFee, w.feeWithParent())
 }
 
 // TestWeightEstimatorMaxFee tests that the weight estimator correctly caps the
@@ -118,7 +120,7 @@ func TestWeightEstimatorMaxFee(t *testing.T) {
 	//
 	// Thus we cap at the maxFee.
 	expectedFee := maxFeeRate.FeeForWeight(childWeight)
-	require.Equal(t, expectedFee, w.fee())
+	require.Equal(t, expectedFee, w.feeWithParent())
 }
 
 // TestWeightEstimatorAddOutput tests that adding the raw P2WKH output to the