contractcourt/timeout_resolver: extract logic into sweepSecondLevelTransaction

This commit moves the logic for sweeping the confirmed second-level
timeout transaction into its own method.

We do a small change to the logic: When setting the spending tx in the
report, we use the detected commitspend instead of the presigned tiemout
tx. This is to prepare for the coming change where the spending
transaction might actually be a re-signed timeout tx, and will therefore
have a different txid.

contractcourt/htlc_timeout_resolver_test.go

@@ -3,6 +3,7 @@ package contractcourt
 import (
 	"bytes"
 	"fmt"
+	"reflect"
 	"sync"
 	"testing"
 	"time"
@@ -17,6 +18,7 @@ import (
 	"github.com/lightningnetwork/lnd/lntest/mock"
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/lnwallet"
+	"github.com/stretchr/testify/require"
 )
 
 type mockWitnessBeacon struct {
@@ -127,6 +129,16 @@ func TestHtlcTimeoutResolver(t *testing.T) {
 					return nil, err
 				}
 
+				// To avoid triggering the race detector by
+				// setting the witness the second time this
+				// method is called during tests, we return
+				// immediately if the witness is already set
+				// correctly.
+				if reflect.DeepEqual(
+					templateTx.TxIn[0].Witness, witness,
+				) {
+					return templateTx, nil
+				}
 				templateTx.TxIn[0].Witness = witness
 				return templateTx, nil
 			},
@@ -148,6 +160,17 @@ func TestHtlcTimeoutResolver(t *testing.T) {
 					return nil, err
 				}
 
+				// To avoid triggering the race detector by
+				// setting the witness the second time this
+				// method is called during tests, we return
+				// immediately if the witness is already set
+				// correctly.
+				if reflect.DeepEqual(
+					templateTx.TxIn[0].Witness, witness,
+				) {
+					return templateTx, nil
+				}
+
 				templateTx.TxIn[0].Witness = witness
 
 				// Set the outpoint to be on our commitment, since
@@ -174,6 +197,17 @@ func TestHtlcTimeoutResolver(t *testing.T) {
 					return nil, err
 				}
 
+				// To avoid triggering the race detector by
+				// setting the witness the second time this
+				// method is called during tests, we return
+				// immediately if the witness is already set
+				// correctly.
+				if reflect.DeepEqual(
+					templateTx.TxIn[0].Witness, witness,
+				) {
+					return templateTx, nil
+				}
+
 				templateTx.TxIn[0].Witness = witness
 				return templateTx, nil
 			},
@@ -196,6 +230,17 @@ func TestHtlcTimeoutResolver(t *testing.T) {
 					return nil, err
 				}
 
+				// To avoid triggering the race detector by
+				// setting the witness the second time this
+				// method is called during tests, we return
+				// immediately if the witness is already set
+				// correctly.
+				if reflect.DeepEqual(
+					templateTx.TxIn[0].Witness, witness,
+				) {
+					return templateTx, nil
+				}
+
 				templateTx.TxIn[0].Witness = witness
 				return templateTx, nil
 			},
@@ -282,16 +327,19 @@ func TestHtlcTimeoutResolver(t *testing.T) {
 		// broadcast, then we'll set the timeout commit to a fake
 		// transaction to force the code path.
 		if !testCase.remoteCommit {
-			resolver.htlcResolution.SignedTimeoutTx = sweepTx
+			timeoutTx, err := testCase.txToBroadcast()
+			require.NoError(t, err)
+
+			resolver.htlcResolution.SignedTimeoutTx = timeoutTx
 
 			if testCase.timeout {
-				success := sweepTx.TxHash()
+				timeoutTxID := timeoutTx.TxHash()
 				reports = append(reports, &channeldb.ResolverReport{
-					OutPoint:        sweepTx.TxIn[0].PreviousOutPoint,
+					OutPoint:        timeoutTx.TxIn[0].PreviousOutPoint,
 					Amount:          testHtlcAmt.ToSatoshis(),
 					ResolverType:    channeldb.ResolverTypeOutgoingHtlc,
 					ResolverOutcome: channeldb.ResolverOutcomeFirstStage,
-					SpendTxID:       &success,
+					SpendTxID:       &timeoutTxID,
 				})
 			}
 		}