discovery: fix incorrect test, masked by loop scoping bug

When we first go to boot up the syncer, when we're in the active phase,
after we do the historical sync, we'll send a timestamp message that we
want everything, then transition to the passive mode. The test didn't
account for this extra message before, as the last test was being
re-used here (ran in parallel).

We fix this by asserting that the first expected message is sent, then
also the follow up messages as well.

discovery/chan_series.go

@@ -163,6 +163,8 @@ func (c *ChanSeries) UpdatesInHorizon(chain chainhash.Hash,
 		return nil, err
 	}
 	for _, nodeAnn := range nodeAnnsInHorizon {
+		nodeAnn := nodeAnn
+
 		// Ensure we only forward nodes that are publicly advertised to
 		// prevent leaking information about nodes.
 		isNodePublic, err := c.graph.IsPublicNode(nodeAnn.PubKeyBytes)

discovery/syncer_test.go

@@ -2134,18 +2134,33 @@ func TestGossipSyncerSyncTransitions(t *testing.T) {
 			name:          "active to passive",
 			entrySyncType: ActiveSync,
 			finalSyncType: PassiveSync,
-			assert: func(t *testing.T, msgChan chan []lnwire.Message,
+			assert: func(t *testing.T, mChan chan []lnwire.Message,
 				g *GossipSyncer) {
 
+				// When we first boot up, we expect that we
+				// send out a message that indicates we want
+				// all the updates from here on.
+				firstTimestamp := uint32(time.Now().Unix())
+				assertMsgSent(
+					t, mChan, &lnwire.GossipTimestampRange{
+						FirstTimestamp: firstTimestamp,
+						TimestampRange: math.MaxUint32,
+					},
+				)
+
 				// When transitioning from active to passive, we
 				// should expect to see a new local update
 				// horizon sent to the remote peer indicating
 				// that it would not like to receive any future
 				// updates.
-				assertMsgSent(t, msgChan, &lnwire.GossipTimestampRange{
-					FirstTimestamp: uint32(zeroTimestamp.Unix()),
-					TimestampRange: 0,
-				})
+				assertMsgSent(
+					t, mChan, &lnwire.GossipTimestampRange{
+						FirstTimestamp: uint32(
+							zeroTimestamp.Unix(),
+						),
+						TimestampRange: 0,
+					},
+				)
 
 				syncState := g.syncState()
 				if syncState != chansSynced {
@@ -2182,6 +2197,8 @@ func TestGossipSyncerSyncTransitions(t *testing.T) {
 	}
 
 	for _, test := range tests {
+		test := test
+
 		t.Run(test.name, func(t *testing.T) {
 			t.Parallel()