lnwallet: expand chan sync tests to cover taproot channels

In this commit, we expand some of the existing chan sync tests to cover
taproot channels (the others already did). Along the way, we always
assert that the `PartialSig` is populated on retransmission. In
addition, we now send the new commit sig rather than the existing
in-memory one to test the new logic that re-signs the commitment.

Author: Roasbeef

lnwallet/channel_test.go

@@ -3046,19 +3046,11 @@ func restartChannel(channelOld *LightningChannel) (*LightningChannel, error) {
 	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) {
-	t.Parallel()
-
+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, channeldb.SingleFunderTweaklessBit,
-	)
+	aliceChannel, bobChannel, err := CreateTestChannels(t, chanType)
 	require.NoError(t, err, "unable to create test channels")
 
 	var fakeOnionBlob [lnwire.OnionPacketSize]byte
@@ -3133,6 +3125,15 @@ func TestChanSyncOweCommitment(t *testing.T) {
 	aliceNewCommit, err := aliceChannel.SignNextCommitment()
 	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.
@@ -3144,7 +3145,7 @@ func TestChanSyncOweCommitment(t *testing.T) {
 	// 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() {
+	assertAliceCommitRetransmit := func() *lnwire.CommitSig {
 		aliceMsgsToSend, _, _, err := aliceChannel.ProcessChanSyncMsg(
 			bobSyncMsg,
 		)
@@ -3209,12 +3210,25 @@ func TestChanSyncOweCommitment(t *testing.T) {
 				len(commitSigMsg.HtlcSigs))
 		}
 		for i, htlcSig := range commitSigMsg.HtlcSigs {
-			if htlcSig != aliceNewCommit.HtlcSigs[i] {
+			if !bytes.Equal(htlcSig.RawBytes(),
+				aliceNewCommit.HtlcSigs[i].RawBytes()) {
+
 				t.Fatalf("htlc sig msgs don't match: "+
-					"expected %x got %x",
-					aliceNewCommit.HtlcSigs[i], htlcSig)
+					"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
@@ -3235,14 +3249,19 @@ func TestChanSyncOweCommitment(t *testing.T) {
 	// send the exact same set of messages.
 	aliceChannel, err = restartChannel(aliceChannel)
 	require.NoError(t, err, "unable to restart alice")
-	assertAliceCommitRetransmit()
 
-	// TODO(roasbeef): restart bob as well???
+	// 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(aliceNewCommit.CommitSigs)
+	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")
@@ -3329,16 +3348,53 @@ func TestChanSyncOweCommitment(t *testing.T) {
 	}
 }
 
-// TestChanSyncOweCommitmentPendingRemote asserts that local updates are applied
-// to the remote commit across restarts.
-func TestChanSyncOweCommitmentPendingRemote(t *testing.T) {
+// 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)
+		})
+	}
+}
+
+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, channeldb.SingleFunderTweaklessBit,
-	)
+	aliceChannel, bobChannel, err := CreateTestChannels(t, chanType)
 	require.NoError(t, err, "unable to create test channels")
 
 	var fakeOnionBlob [lnwire.OnionPacketSize]byte
@@ -3421,6 +3477,12 @@ func TestChanSyncOweCommitmentPendingRemote(t *testing.T) {
 	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()
 	require.NoError(t, err, "unable to sign commitment")
@@ -3446,6 +3508,45 @@ func TestChanSyncOweCommitmentPendingRemote(t *testing.T) {
 	}
 }
 
+// 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.
@@ -3595,8 +3696,6 @@ func testChanSyncOweRevocation(t *testing.T, chanType channeldb.ChannelType) {
 
 	assertAliceOwesRevoke()
 
-	// TODO(roasbeef): restart bob too???
-
 	// We'll continue by then allowing bob to process Alice's revocation
 	// message.
 	_, _, _, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
@@ -3645,6 +3744,15 @@ func TestChanSyncOweRevocation(t *testing.T) {
 
 		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,
@@ -3774,6 +3882,14 @@ func testChanSyncOweRevocationAndCommit(t *testing.T,
 					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
@@ -3830,6 +3946,15 @@ func TestChanSyncOweRevocationAndCommit(t *testing.T) {
 
 		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,
@@ -4061,6 +4186,17 @@ func TestChanSyncOweRevocationAndCommitForceTransition(t *testing.T) {
 			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