itest: add new RBF coop close itest

The itest has both sides try to close multiple times, each time with
increasing fee rates.

itest/list_on_test.go

@@ -678,4 +678,8 @@ var allTestCases = []*lntest.TestCase{
 		Name:     "send to route failed htlc timeout",
 		TestFunc: testSendToRouteFailHTLCTimeout,
 	},
+	{
+		Name:     "rbf coop close",
+		TestFunc: testCoopCloseRbf,
+	},
 }

itest/lnd_coop_close_rbf_test.go

@@ -0,0 +1,117 @@
+package itest
+
+import (
+	"github.com/btcsuite/btcd/btcutil"
+	"github.com/lightningnetwork/lnd/lntest"
+	"github.com/lightningnetwork/lnd/lnwallet/chainfee"
+	"github.com/stretchr/testify/require"
+)
+
+func testCoopCloseRbf(ht *lntest.HarnessTest) {
+	rbfCoopFlags := []string{"--protocol.rbf-coop-close"}
+
+	// Set the fee estimate to 1sat/vbyte. This ensures that our manually
+	// initiated RBF attempts will always be successful.
+	ht.SetFeeEstimate(250)
+	ht.SetFeeEstimateWithConf(250, 6)
+
+	// To kick things off, we'll create two new nodes, then fund them with
+	// enough coins for the test below.
+	alice := ht.NewNode("Carol", rbfCoopFlags)
+	defer ht.Shutdown(alice)
+
+	bob := ht.NewNode("Dave", rbfCoopFlags)
+	defer ht.Shutdown(bob)
+
+	// With the nodes active, we'll fund Alice's wallet, connect them, then
+	// fund enough coins to make a 50/50 channel.
+	ht.FundCoins(btcutil.SatoshiPerBitcoin, alice)
+	ht.ConnectNodes(alice, bob)
+	chanPoint := ht.OpenChannel(alice, bob, lntest.OpenChannelParams{
+		Amt:     btcutil.Amount(1000000),
+		PushAmt: btcutil.Amount(1000000 / 2),
+	})
+
+	// Now that both sides are active with a funded channel, we can kick
+	// off the test.
+	//
+	// To start, we'll have Alice try to close the channel, with a fee rate
+	// of 5 sat/byte.
+	aliceFeeRate := chainfee.SatPerVByte(5)
+	aliceCloseStream, aliceCloseUpdate := ht.CloseChannelAssertPending(
+		alice, chanPoint, false,
+		lntest.WithCoopCloseFeeRate(aliceFeeRate),
+	)
+
+	// Confirm that this new update was at 5 sat/vb.
+	alicePendingUpdate := aliceCloseUpdate.GetClosePending()
+	require.NotNil(ht, aliceCloseUpdate)
+	require.Equal(
+		ht, int64(aliceFeeRate), alicePendingUpdate.FeeRatePerVbyte,
+	)
+	require.True(ht, alicePendingUpdate.LocalCloseTx)
+
+	// Now, we'll have Bob attempt to RBF the close transaction with a
+	// higher fee rate, double that of Alice's.
+	bobFeeRate := aliceFeeRate * 2
+	bobCloseStream, bobCloseUpdate := ht.CloseChannelAssertPending(
+		bob, chanPoint, false, lntest.WithCoopCloseFeeRate(bobFeeRate),
+	)
+
+	// Confirm that this new update was at 10 sat/vb.
+	bobPendingUpdate := bobCloseUpdate.GetClosePending()
+	require.NotNil(ht, bobCloseUpdate)
+	require.Equal(ht, bobPendingUpdate.FeeRatePerVbyte, int64(bobFeeRate))
+	require.True(ht, bobPendingUpdate.LocalCloseTx)
+
+	var err error
+
+	// Alice should've also received a similar update that Bob has
+	// increased the closing fee rate to 10 sat/vb with his settled funds.
+	aliceCloseUpdate, err = aliceCloseStream.Recv()
+	require.NoError(ht, err)
+	alicePendingUpdate = aliceCloseUpdate.GetClosePending()
+	require.NotNil(ht, aliceCloseUpdate)
+	require.Equal(ht, alicePendingUpdate.FeeRatePerVbyte, int64(bobFeeRate))
+	require.False(ht, alicePendingUpdate.LocalCloseTx)
+
+	// Next, we'll have Alice double that fee rate again to 20 sat/vb.
+	aliceFeeRate = bobFeeRate * 2
+	_, aliceCloseUpdate = ht.CloseChannelAssertPending(
+		alice, chanPoint, false,
+		lntest.WithCoopCloseFeeRate(aliceFeeRate),
+	)
+	alicePendingUpdate = aliceCloseUpdate.GetClosePending()
+	require.NotNil(ht, aliceCloseUpdate)
+	require.Equal(
+		ht, alicePendingUpdate.FeeRatePerVbyte, int64(aliceFeeRate),
+	)
+	require.True(ht, alicePendingUpdate.LocalCloseTx)
+
+	// Bob should've also received a similar update that Alice has
+	// increased the closing fee rate to 20 sat/vb with his settled funds.
+	bobCloseUpdate, err = bobCloseStream.Recv()
+	require.NoError(ht, err)
+	bobPendingUpdate = bobCloseUpdate.GetClosePending()
+	require.NotNil(ht, bobCloseUpdate)
+	require.Equal(
+		ht, bobPendingUpdate.FeeRatePerVbyte, int64(aliceFeeRate),
+	)
+	require.False(ht, bobPendingUpdate.LocalCloseTx)
+
+	// Consume Alice's stream update, this is a duplicate of the one we
+	// checked above.
+	_, err = aliceCloseStream.Recv()
+	require.NoError(ht, err)
+
+	// To conclude, we'll mine a block which should now confirm Alice's
+	// version of the coop close transaction.
+	block := ht.MineBlocksAndAssertNumTxes(1, 1)[0]
+
+	// Both Alice and Bob should trigger a final close update to signal the
+	// closing transaction has confirmed.
+	aliceClosingTxid := ht.WaitForChannelCloseEvent(aliceCloseStream)
+	bobClosingTxid := ht.WaitForChannelCloseEvent(bobCloseStream)
+	require.Equal(ht, aliceClosingTxid, bobClosingTxid)
+	ht.Miner.AssertTxInBlock(block, aliceClosingTxid)
+}