itest: refactor taproot test

lntest/itest/lnd_taproot_test.go

@@ -23,29 +23,43 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+const (
+	testTaprootKeyFamily = 77
+	testAmount           = 800_000
+)
+
+var (
+	dummyInternalKeyBytes, _ = hex.DecodeString(
+		"03464805f5468e294d88cf15a3f06aef6c89d63ef1bd7b42db2e0c74c1ac" +
+			"eb90fe",
+	)
+	dummyInternalKey, _ = btcec.ParsePubKey(dummyInternalKeyBytes)
+)
+
 // testTaproot ensures that the daemon can send to and spend from taproot (p2tr)
 // outputs.
 func testTaproot(net *lntest.NetworkHarness, t *harnessTest) {
 	ctxb := context.Background()
-	ctxt, cancel := context.WithTimeout(ctxb, defaultTimeout)
+	ctxt, cancel := context.WithTimeout(ctxb, 2*defaultTimeout)
 	defer cancel()
 
-	testTaprootKeySpend(ctxt, t, net)
+	testTaprootComputeInputScriptKeySpendBip86(ctxt, t, net.Alice, net)
-	testTaprootScriptSpend(ctxt, t, net)
+	testTaprootSignOutputRawScriptSpend(ctxt, t, net.Alice, net)
-	testTaprootKeySpendRPC(ctxt, t, net)
+	testTaprootSignOutputRawKeySpendRootHash(ctxt, t, net.Alice, net)
 }
 
-// testTaprootKeySpend tests sending to and spending from p2tr key spend only
+// testTaprootComputeInputScriptKeySpendBip86 tests sending to and spending from
-// (BIP-0086) addresses.
+// p2tr key spend only (BIP-0086) addresses through the SendCoins RPC which
-func testTaprootKeySpend(ctxt context.Context, t *harnessTest,
+// internally uses the ComputeInputScript method for signing.
-	net *lntest.NetworkHarness) {
+func testTaprootComputeInputScriptKeySpendBip86(ctxt context.Context,
+	t *harnessTest, alice *lntest.HarnessNode, net *lntest.NetworkHarness) {
 
 	// We'll start the test by sending Alice some coins, which she'll use to
 	// send to herself on a p2tr output.
-	net.SendCoins(t.t, btcutil.SatoshiPerBitcoin, net.Alice)
+	net.SendCoins(t.t, btcutil.SatoshiPerBitcoin, alice)
 
 	// Let's create a p2tr address now.
-	p2trResp, err := net.Alice.NewAddress(ctxt, &lnrpc.NewAddressRequest{
+	p2trResp, err := alice.NewAddress(ctxt, &lnrpc.NewAddressRequest{
 		Type: lnrpc.AddressType_TAPROOT_PUBKEY,
 	})
 	require.NoError(t.t, err)
@@ -57,7 +71,7 @@ func testTaprootKeySpend(ctxt context.Context, t *harnessTest,
 
 	// Send the coins from Alice's wallet to her own, but to the new p2tr
 	// address.
-	_, err = net.Alice.SendCoins(ctxt, &lnrpc.SendCoinsRequest{
+	_, err = alice.SendCoins(ctxt, &lnrpc.SendCoinsRequest{
 		Addr:   p2trResp.Address,
 		Amount: 0.5 * btcutil.SatoshiPerBitcoin,
 	})
@@ -72,80 +86,38 @@ func testTaprootKeySpend(ctxt context.Context, t *harnessTest,
 		TxidBytes:   txid[:],
 		OutputIndex: uint32(p2trOutputIndex),
 	}
-	assertWalletUnspent(t, net.Alice, op)
+	assertWalletUnspent(t, alice, op)
 
 	// Mine a block to clean up the mempool.
 	mineBlocks(t, net, 1, 1)
 
 	// Let's sweep the whole wallet to a new p2tr address, making sure we
 	// can sign transactions with v0 and v1 inputs.
-	p2trResp, err = net.Alice.NewAddress(ctxt, &lnrpc.NewAddressRequest{
+	p2trResp, err = alice.NewAddress(ctxt, &lnrpc.NewAddressRequest{
 		Type: lnrpc.AddressType_TAPROOT_PUBKEY,
 	})
 	require.NoError(t.t, err)
 
-	_, err = net.Alice.SendCoins(ctxt, &lnrpc.SendCoinsRequest{
+	_, err = alice.SendCoins(ctxt, &lnrpc.SendCoinsRequest{
 		Addr:    p2trResp.Address,
 		SendAll: true,
 	})
 	require.NoError(t.t, err)
 
-	// Wait until the wallet cleaning sweep tx is found.
+	// Make sure the coins sent to the address are confirmed correctly,
-	txid, err = waitForTxInMempool(net.Miner.Client, minerMempoolTimeout)
+	// including the confirmation notification.
-	require.NoError(t.t, err)
+	confirmAddress(ctxt, t, net, alice, p2trResp.Address)
-
-	// Wait until bob has seen the tx and considers it as owned.
-	p2trOutputIndex = getOutputIndex(t, net.Miner, txid, p2trResp.Address)
-	op = &lnrpc.OutPoint{
-		TxidBytes:   txid[:],
-		OutputIndex: uint32(p2trOutputIndex),
-	}
-	assertWalletUnspent(t, net.Alice, op)
-
-	// Before we confirm the transaction, let's register a confirmation
-	// listener for it, which we expect to fire after mining a block.
-	p2trAddr, err := btcutil.DecodeAddress(
-		p2trResp.Address, harnessNetParams,
-	)
-	require.NoError(t.t, err)
-	p2trPkScript, err := txscript.PayToAddrScript(p2trAddr)
-	require.NoError(t.t, err)
-
-	_, currentHeight, err := net.Miner.Client.GetBestBlock()
-	require.NoError(t.t, err)
-	confClient, err := net.Alice.ChainClient.RegisterConfirmationsNtfn(
-		ctxt, &chainrpc.ConfRequest{
-			Script:     p2trPkScript,
-			Txid:       txid[:],
-			HeightHint: uint32(currentHeight),
-			NumConfs:   1,
-		},
-	)
-	require.NoError(t.t, err)
-
-	// Mine another block to clean up the mempool.
-	mineBlocks(t, net, 1, 1)
-
-	// We now expect our confirmation to go through.
-	confMsg, err := confClient.Recv()
-	require.NoError(t.t, err)
-	conf := confMsg.GetConf()
-	require.NotNil(t.t, conf)
-	require.Equal(t.t, conf.BlockHeight, uint32(currentHeight+1))
 }
 
-// testTaprootScriptSpend tests sending to and spending from p2tr script
+// testTaprootSignOutputRawScriptSpend tests sending to and spending from p2tr
-// addresses.
+// script addresses using the script path with the SignOutputRaw RPC.
-func testTaprootScriptSpend(ctxt context.Context, t *harnessTest,
+func testTaprootSignOutputRawScriptSpend(ctxt context.Context, t *harnessTest,
-	net *lntest.NetworkHarness) {
+	alice *lntest.HarnessNode, net *lntest.NetworkHarness) {
 
 	// For the next step, we need a public key. Let's use a special family
 	// for this.
-	const taprootKeyFamily = 77
+	keyDesc, err := alice.WalletKitClient.DeriveNextKey(
-	keyDesc, err := net.Alice.WalletKitClient.DeriveNextKey(
+		ctxt, &walletrpc.KeyReq{KeyFamily: testTaprootKeyFamily},
-		ctxt, &walletrpc.KeyReq{
-			KeyFamily: taprootKeyFamily,
-		},
 	)
 	require.NoError(t.t, err)
 
@@ -159,50 +131,20 @@ func testTaprootScriptSpend(ctxt context.Context, t *harnessTest,
 	// Let's add a second script output as well to test the partial reveal.
 	leaf2 := testScriptSchnorrSig(t.t, leafSigningKey)
 
-	dummyInternalKeyBytes, _ := hex.DecodeString(
-		"03464805f5468e294d88cf15a3f06aef6c89d63ef1bd7b42db2e0c74c1ac" +
-			"eb90fe",
-	)
-	dummyInternalKey, _ := btcec.ParsePubKey(dummyInternalKeyBytes)
-
 	tapscript := input.TapscriptPartialReveal(
 		dummyInternalKey, leaf2, leaf1.TapHash(),
 	)
 	taprootKey, err := tapscript.TaprootKey()
 	require.NoError(t.t, err)
 
-	tapScriptAddr, err := btcutil.NewAddressTaproot(
-		schnorr.SerializePubKey(taprootKey), harnessNetParams,
-	)
-	require.NoError(t.t, err)
-	p2trPkScript, err := txscript.PayToAddrScript(tapScriptAddr)
-	require.NoError(t.t, err)
-
 	// Send some coins to the generated tapscript address.
-	_, err = net.Alice.SendCoins(ctxt, &lnrpc.SendCoinsRequest{
+	p2trOutpoint, p2trPkScript := sendToTaprootOutput(
-		Addr:   tapScriptAddr.String(),
+		ctxt, t, net, alice, taprootKey, testAmount,
-		Amount: 800_000,
-	})
-	require.NoError(t.t, err)
-
-	// Wait until the TX is found in the mempool.
-	txid, err := waitForTxInMempool(net.Miner.Client, minerMempoolTimeout)
-	require.NoError(t.t, err)
-
-	p2trOutputIndex := getOutputIndex(
-		t, net.Miner, txid, tapScriptAddr.String(),
 	)
-	p2trOutpoint := wire.OutPoint{
-		Hash:  *txid,
-		Index: uint32(p2trOutputIndex),
-	}
-
-	// Clear the mempool.
-	mineBlocks(t, net, 1, 1)
 
 	// Spend the output again, this time back to a p2wkh address.
 	p2wkhAddr, p2wkhPkScript := newAddrWithScript(
-		ctxt, t.t, net.Alice, lnrpc.AddressType_WITNESS_PUBKEY_HASH,
+		ctxt, t.t, alice, lnrpc.AddressType_WITNESS_PUBKEY_HASH,
 	)
 
 	// Create fee estimation for a p2tr input and p2wkh output.
@@ -219,7 +161,7 @@ func testTaprootScriptSpend(ctxt context.Context, t *harnessTest,
 	tx.TxIn = []*wire.TxIn{{
 		PreviousOutPoint: p2trOutpoint,
 	}}
-	value := int64(800_000 - requiredFee)
+	value := int64(testAmount - requiredFee)
 	tx.TxOut = []*wire.TxOut{{
 		PkScript: p2wkhPkScript,
 		Value:    value,
@@ -230,13 +172,13 @@ func testTaprootScriptSpend(ctxt context.Context, t *harnessTest,
 
 	utxoInfo := []*signrpc.TxOut{{
 		PkScript: p2trPkScript,
-		Value:    800_000,
+		Value:    testAmount,
 	}}
 
 	// Before we actually sign, we want to make sure that we get an error
 	// when we try to sign for a Taproot output without specifying all UTXO
 	// information.
-	_, err = net.Alice.SignerClient.SignOutputRaw(
+	_, err = alice.SignerClient.SignOutputRaw(
 		ctxt, &signrpc.SignReq{
 			RawTxBytes: buf.Bytes(),
 			SignDescs: []*signrpc.SignDescriptor{{
@@ -255,7 +197,7 @@ func testTaprootScriptSpend(ctxt context.Context, t *harnessTest,
 	)
 
 	// Do the actual signing now.
-	signResp, err := net.Alice.SignerClient.SignOutputRaw(
+	signResp, err := alice.SignerClient.SignOutputRaw(
 		ctxt, &signrpc.SignReq{
 			RawTxBytes: buf.Bytes(),
 			SignDescs: []*signrpc.SignDescriptor{{
@@ -280,93 +222,31 @@ func testTaprootScriptSpend(ctxt context.Context, t *harnessTest,
 		controlBlockBytes,
 	}
 
-	buf.Reset()
+	// Serialize, weigh and publish the TX now, then make sure the
-	require.NoError(t.t, tx.Serialize(&buf))
+	// coins are sent and confirmed to the final sweep destination address.
-
+	publishTxAndConfirmSweep(
-	// Since Schnorr signatures are fixed size, we must be able to estimate
+		ctxt, t, net, alice, tx, estimatedWeight,
-	// the size of this transaction exactly.
+		&chainrpc.SpendRequest{
-	txWeight := blockchain.GetTransactionWeight(btcutil.NewTx(tx))
-	require.Equal(t.t, txWeight, estimatedWeight)
-
-	// Before we publish the tx that spends the p2tr transaction, we want to
-	// register a spend listener that we expect to fire after mining the
-	// block.
-	_, currentHeight, err := net.Miner.Client.GetBestBlock()
-	require.NoError(t.t, err)
-
-	// For a Taproot output we cannot leave the outpoint empty. Let's make
-	// sure the API returns the correct error here.
-	spendClient, err := net.Alice.ChainClient.RegisterSpendNtfn(
-		ctxt, &chainrpc.SpendRequest{
-			Script:     p2trPkScript,
-			HeightHint: uint32(currentHeight),
-		},
-	)
-	require.NoError(t.t, err)
-
-	// The error is only thrown when trying to read a message.
-	_, err = spendClient.Recv()
-	require.Contains(
-		t.t, err.Error(),
-		"cannot register witness v1 spend request without outpoint",
-	)
-
-	// Now try again, this time with the outpoint set.
-	spendClient, err = net.Alice.ChainClient.RegisterSpendNtfn(
-		ctxt, &chainrpc.SpendRequest{
 			Outpoint: &chainrpc.Outpoint{
 				Hash:  p2trOutpoint.Hash[:],
 				Index: p2trOutpoint.Index,
 			},
-			Script:     p2trPkScript,
+			Script: p2trPkScript,
-			HeightHint: uint32(currentHeight),
 		},
+		p2wkhAddr.String(),
 	)
-	require.NoError(t.t, err)
-
-	_, err = net.Alice.WalletKitClient.PublishTransaction(
-		ctxt, &walletrpc.Transaction{
-			TxHex: buf.Bytes(),
-		},
-	)
-	require.NoError(t.t, err)
-
-	// Wait until the spending tx is found.
-	txid, err = waitForTxInMempool(net.Miner.Client, minerMempoolTimeout)
-	require.NoError(t.t, err)
-	p2wpkhOutputIndex := getOutputIndex(
-		t, net.Miner, txid, p2wkhAddr.String(),
-	)
-	op := &lnrpc.OutPoint{
-		TxidBytes:   txid[:],
-		OutputIndex: uint32(p2wpkhOutputIndex),
-	}
-	assertWalletUnspent(t, net.Alice, op)
-
-	// Mine another block to clean up the mempool and to make sure the spend
-	// tx is actually included in a block.
-	mineBlocks(t, net, 1, 1)
-
-	// We now expect our spend event to go through.
-	spendMsg, err := spendClient.Recv()
-	require.NoError(t.t, err)
-	spend := spendMsg.GetSpend()
-	require.NotNil(t.t, spend)
-	require.Equal(t.t, spend.SpendingHeight, uint32(currentHeight+1))
 }
 
-// testTaprootKeySpendRPC tests that a tapscript address can also be spent using
+// testTaprootSignOutputRawKeySpendRootHash tests that a tapscript address can
-// the key spend path through the RPC.
+// also be spent using the key spend path through the SignOutputRaw RPC using a
-func testTaprootKeySpendRPC(ctxt context.Context, t *harnessTest,
+// tapscript root hash.
-	net *lntest.NetworkHarness) {
+func testTaprootSignOutputRawKeySpendRootHash(ctxt context.Context,
+	t *harnessTest, alice *lntest.HarnessNode, net *lntest.NetworkHarness) {
 
 	// For the next step, we need a public key. Let's use a special family
 	// for this.
-	const taprootKeyFamily = 77
+	keyDesc, err := alice.WalletKitClient.DeriveNextKey(
-	keyDesc, err := net.Alice.WalletKitClient.DeriveNextKey(
+		ctxt, &walletrpc.KeyReq{KeyFamily: testTaprootKeyFamily},
-		ctxt, &walletrpc.KeyReq{
-			KeyFamily: taprootKeyFamily,
-		},
 	)
 	require.NoError(t.t, err)
 
@@ -385,34 +265,14 @@ func testTaprootKeySpendRPC(ctxt context.Context, t *harnessTest,
 	rootHash := leaf1.TapHash()
 	taprootKey := txscript.ComputeTaprootOutputKey(internalKey, rootHash[:])
 
-	tapScriptAddr, err := btcutil.NewAddressTaproot(
-		schnorr.SerializePubKey(taprootKey), harnessNetParams,
-	)
-	require.NoError(t.t, err)
-	p2trPkScript, err := txscript.PayToAddrScript(tapScriptAddr)
-	require.NoError(t.t, err)
-
 	// Send some coins to the generated tapscript address.
-	_, err = net.Alice.SendCoins(ctxt, &lnrpc.SendCoinsRequest{
+	p2trOutpoint, p2trPkScript := sendToTaprootOutput(
-		Addr:   tapScriptAddr.String(),
+		ctxt, t, net, alice, taprootKey, testAmount,
-		Amount: 800_000,
-	})
-	require.NoError(t.t, err)
-
-	// Wait until the TX is found in the mempool.
-	txid, err := waitForTxInMempool(net.Miner.Client, minerMempoolTimeout)
-	require.NoError(t.t, err)
-
-	p2trOutputIndex := getOutputIndex(
-		t, net.Miner, txid, tapScriptAddr.String(),
 	)
 
-	// Clear the mempool.
-	mineBlocks(t, net, 1, 1)
-
 	// Spend the output again, this time back to a p2wkh address.
 	p2wkhAddr, p2wkhPkScript := newAddrWithScript(
-		ctxt, t.t, net.Alice, lnrpc.AddressType_WITNESS_PUBKEY_HASH,
+		ctxt, t.t, alice, lnrpc.AddressType_WITNESS_PUBKEY_HASH,
 	)
 
 	// Create fee estimation for a p2tr input and p2wkh output.
@@ -425,12 +285,9 @@ func testTaprootKeySpendRPC(ctxt context.Context, t *harnessTest,
 
 	tx := wire.NewMsgTx(2)
 	tx.TxIn = []*wire.TxIn{{
-		PreviousOutPoint: wire.OutPoint{
+		PreviousOutPoint: p2trOutpoint,
-			Hash:  *txid,
-			Index: uint32(p2trOutputIndex),
-		},
 	}}
-	value := int64(800_000 - requiredFee)
+	value := int64(testAmount - requiredFee)
 	tx.TxOut = []*wire.TxOut{{
 		PkScript: p2wkhPkScript,
 		Value:    value,
@@ -441,9 +298,9 @@ func testTaprootKeySpendRPC(ctxt context.Context, t *harnessTest,
 
 	utxoInfo := []*signrpc.TxOut{{
 		PkScript: p2trPkScript,
-		Value:    800_000,
+		Value:    testAmount,
 	}}
-	signResp, err := net.Alice.SignerClient.SignOutputRaw(
+	signResp, err := alice.SignerClient.SignOutputRaw(
 		ctxt, &signrpc.SignReq{
 			RawTxBytes: buf.Bytes(),
 			SignDescs: []*signrpc.SignDescriptor{{
@@ -464,36 +321,19 @@ func testTaprootKeySpendRPC(ctxt context.Context, t *harnessTest,
 		signResp.RawSigs[0],
 	}
 
-	buf.Reset()
+	// Serialize, weigh and publish the TX now, then make sure the
-	require.NoError(t.t, tx.Serialize(&buf))
+	// coins are sent and confirmed to the final sweep destination address.
-
+	publishTxAndConfirmSweep(
-	// Since Schnorr signatures are fixed size, we must be able to estimate
+		ctxt, t, net, alice, tx, estimatedWeight,
-	// the size of this transaction exactly.
+		&chainrpc.SpendRequest{
-	txWeight := blockchain.GetTransactionWeight(btcutil.NewTx(tx))
+			Outpoint: &chainrpc.Outpoint{
-	require.Equal(t.t, txWeight, estimatedWeight)
+				Hash:  p2trOutpoint.Hash[:],
-
+				Index: p2trOutpoint.Index,
-	_, err = net.Alice.WalletKitClient.PublishTransaction(
+			},
-		ctxt, &walletrpc.Transaction{
+			Script: p2trPkScript,
-			TxHex: buf.Bytes(),
 		},
+		p2wkhAddr.String(),
 	)
-	require.NoError(t.t, err)
-
-	// Wait until the spending tx is found.
-	txid, err = waitForTxInMempool(net.Miner.Client, minerMempoolTimeout)
-	require.NoError(t.t, err)
-	p2wpkhOutputIndex := getOutputIndex(
-		t, net.Miner, txid, p2wkhAddr.String(),
-	)
-	op := &lnrpc.OutPoint{
-		TxidBytes:   txid[:],
-		OutputIndex: uint32(p2wpkhOutputIndex),
-	}
-	assertWalletUnspent(t, net.Alice, op)
-
-	// Mine another block to clean up the mempool and to make sure the spend
-	// tx is actually included in a block.
-	mineBlocks(t, net, 1, 1)
 }
 
 // testScriptHashLock returns a simple bitcoin script that locks the funds to
@@ -542,3 +382,159 @@ func newAddrWithScript(ctx context.Context, t *testing.T,
 
 	return p2wkhAddr, p2wkhPkScript
 }
+
+// sendToTaprootOutput sends coins to a p2tr output of the given taproot key and
+// mines a block to confirm the coins.
+func sendToTaprootOutput(ctx context.Context, t *harnessTest,
+	net *lntest.NetworkHarness, node *lntest.HarnessNode,
+	taprootKey *btcec.PublicKey, amt int64) (wire.OutPoint, []byte) {
+
+	tapScriptAddr, err := btcutil.NewAddressTaproot(
+		schnorr.SerializePubKey(taprootKey), harnessNetParams,
+	)
+	require.NoError(t.t, err)
+	p2trPkScript, err := txscript.PayToAddrScript(tapScriptAddr)
+	require.NoError(t.t, err)
+
+	// Send some coins to the generated tapscript address.
+	_, err = node.SendCoins(ctx, &lnrpc.SendCoinsRequest{
+		Addr:   tapScriptAddr.String(),
+		Amount: amt,
+	})
+	require.NoError(t.t, err)
+
+	// Wait until the TX is found in the mempool.
+	txid, err := waitForTxInMempool(net.Miner.Client, minerMempoolTimeout)
+	require.NoError(t.t, err)
+
+	p2trOutputIndex := getOutputIndex(
+		t, net.Miner, txid, tapScriptAddr.String(),
+	)
+	p2trOutpoint := wire.OutPoint{
+		Hash:  *txid,
+		Index: uint32(p2trOutputIndex),
+	}
+
+	// Clear the mempool.
+	mineBlocks(t, net, 1, 1)
+
+	return p2trOutpoint, p2trPkScript
+}
+
+// publishTxAndConfirmSweep is a helper function that publishes a transaction
+// after checking its weight against an estimate. After asserting the given
+// spend request, the given sweep address' balance is verified to be seen as
+// funds belonging to the wallet.
+func publishTxAndConfirmSweep(ctx context.Context, t *harnessTest,
+	net *lntest.NetworkHarness, node *lntest.HarnessNode, tx *wire.MsgTx,
+	estimatedWeight int64, spendRequest *chainrpc.SpendRequest,
+	sweepAddr string) {
+
+	// Before we publish the tx that spends the p2tr transaction, we want to
+	// register a spend listener that we expect to fire after mining the
+	// block.
+	_, currentHeight, err := net.Miner.Client.GetBestBlock()
+	require.NoError(t.t, err)
+
+	// For a Taproot output we cannot leave the outpoint empty. Let's make
+	// sure the API returns the correct error here.
+	spendClient, err := node.ChainClient.RegisterSpendNtfn(
+		ctx, &chainrpc.SpendRequest{
+			Script:     spendRequest.Script,
+			HeightHint: uint32(currentHeight),
+		},
+	)
+	require.NoError(t.t, err)
+
+	// The error is only thrown when trying to read a message.
+	_, err = spendClient.Recv()
+	require.Contains(
+		t.t, err.Error(),
+		"cannot register witness v1 spend request without outpoint",
+	)
+
+	// Now try again, this time with the outpoint set.
+	spendClient, err = node.ChainClient.RegisterSpendNtfn(
+		ctx, &chainrpc.SpendRequest{
+			Outpoint:   spendRequest.Outpoint,
+			Script:     spendRequest.Script,
+			HeightHint: uint32(currentHeight),
+		},
+	)
+	require.NoError(t.t, err)
+
+	var buf bytes.Buffer
+	require.NoError(t.t, tx.Serialize(&buf))
+
+	// Since Schnorr signatures are fixed size, we must be able to estimate
+	// the size of this transaction exactly.
+	txWeight := blockchain.GetTransactionWeight(btcutil.NewTx(tx))
+	require.Equal(t.t, estimatedWeight, txWeight)
+
+	_, err = node.WalletKitClient.PublishTransaction(
+		ctx, &walletrpc.Transaction{
+			TxHex: buf.Bytes(),
+		},
+	)
+	require.NoError(t.t, err)
+
+	// Make sure the coins sent to the address are confirmed correctly,
+	// including the confirmation notification.
+	confirmAddress(ctx, t, net, node, sweepAddr)
+
+	// We now expect our spend event to go through.
+	spendMsg, err := spendClient.Recv()
+	require.NoError(t.t, err)
+	spend := spendMsg.GetSpend()
+	require.NotNil(t.t, spend)
+	require.Equal(t.t, spend.SpendingHeight, uint32(currentHeight+1))
+}
+
+// confirmAddress makes sure that a transaction in the mempool spends funds to
+// the given address. It also checks that a confirmation notification for the
+// address is triggered when the transaction is mined.
+func confirmAddress(ctx context.Context, t *harnessTest,
+	net *lntest.NetworkHarness, node *lntest.HarnessNode,
+	addrString string) {
+
+	// Wait until the tx that sends to the address is found.
+	txid, err := waitForTxInMempool(net.Miner.Client, minerMempoolTimeout)
+	require.NoError(t.t, err)
+
+	// Wait until bob has seen the tx and considers it as owned.
+	addrOutputIndex := getOutputIndex(t, net.Miner, txid, addrString)
+	op := &lnrpc.OutPoint{
+		TxidBytes:   txid[:],
+		OutputIndex: uint32(addrOutputIndex),
+	}
+	assertWalletUnspent(t, node, op)
+
+	// Before we confirm the transaction, let's register a confirmation
+	// listener for it, which we expect to fire after mining a block.
+	parsedAddr, err := btcutil.DecodeAddress(addrString, harnessNetParams)
+	require.NoError(t.t, err)
+	addrPkScript, err := txscript.PayToAddrScript(parsedAddr)
+	require.NoError(t.t, err)
+
+	_, currentHeight, err := net.Miner.Client.GetBestBlock()
+	require.NoError(t.t, err)
+	confClient, err := node.ChainClient.RegisterConfirmationsNtfn(
+		ctx, &chainrpc.ConfRequest{
+			Script:     addrPkScript,
+			Txid:       txid[:],
+			HeightHint: uint32(currentHeight),
+			NumConfs:   1,
+		},
+	)
+	require.NoError(t.t, err)
+
+	// Mine another block to clean up the mempool.
+	mineBlocks(t, net, 1, 1)
+
+	// We now expect our confirmation to go through.
+	confMsg, err := confClient.Recv()
+	require.NoError(t.t, err)
+	conf := confMsg.GetConf()
+	require.NotNil(t.t, conf)
+	require.Equal(t.t, conf.BlockHeight, uint32(currentHeight+1))
+}