input/script_utils_test: refactor TestHTLCSenderSpendValidation

To be able to change more than the witness used for each test case, we
extract commit and sweep tx generation into own methods that can be
called from each test case.

We do the same for TestHTLCReceiverSpendValidation

input/script_utils_test.go

@@ -212,43 +212,6 @@ func TestHTLCSenderSpendValidation(t *testing.T) {
 	// we'll be using Bob's base point for the revocation key.
 	revocationKey := DeriveRevocationPubkey(bobKeyPub, commitPoint)
 
-	// Generate the raw HTLC redemption scripts, and its p2wsh counterpart.
-	htlcWitnessScript, err := SenderHTLCScript(aliceLocalKey, bobLocalKey,
-		revocationKey, paymentHash[:])
-	if err != nil {
-		t.Fatalf("unable to create htlc sender script: %v", err)
-	}
-	htlcPkScript, err := WitnessScriptHash(htlcWitnessScript)
-	if err != nil {
-		t.Fatalf("unable to create p2wsh htlc script: %v", err)
-	}
-
-	// This will be Alice's commitment transaction. In this scenario Alice
-	// is sending an HTLC to a node she has a path to (could be Bob, could
-	// be multiple hops down, it doesn't really matter).
-	htlcOutput := &wire.TxOut{
-		Value:    int64(paymentAmt),
-		PkScript: htlcPkScript,
-	}
-	senderCommitTx := wire.NewMsgTx(2)
-	senderCommitTx.AddTxIn(fakeFundingTxIn)
-	senderCommitTx.AddTxOut(htlcOutput)
-
-	prevOut := &wire.OutPoint{
-		Hash:  senderCommitTx.TxHash(),
-		Index: 0,
-	}
-
-	sweepTx := wire.NewMsgTx(2)
-	sweepTx.AddTxIn(wire.NewTxIn(prevOut, nil, nil))
-	sweepTx.AddTxOut(
-		&wire.TxOut{
-			PkScript: []byte("doesn't matter"),
-			Value:    1 * 10e8,
-		},
-	)
-	sweepTxSigHashes := txscript.NewTxSigHashes(sweepTx)
-
 	bobCommitTweak := SingleTweakBytes(commitPoint, bobKeyPub)
 	aliceCommitTweak := SingleTweakBytes(commitPoint, aliceKeyPub)
 
@@ -258,6 +221,63 @@ func TestHTLCSenderSpendValidation(t *testing.T) {
 	bobSigner := &MockSigner{Privkeys: []*btcec.PrivateKey{bobKeyPriv}}
 	aliceSigner := &MockSigner{Privkeys: []*btcec.PrivateKey{aliceKeyPriv}}
 
+	var (
+		htlcWitnessScript, htlcPkScript []byte
+		htlcOutput                      *wire.TxOut
+		sweepTxSigHashes                *txscript.TxSigHashes
+		senderCommitTx, sweepTx         *wire.MsgTx
+		bobRecvrSig                     []byte
+	)
+
+	// genCommitTx generates a commitment tx.
+	genCommitTx := func() {
+		// Generate the raw HTLC redemption scripts, and its p2wsh
+		// counterpart.
+		htlcWitnessScript, err = SenderHTLCScript(
+			aliceLocalKey, bobLocalKey, revocationKey,
+			paymentHash[:],
+		)
+		if err != nil {
+			t.Fatalf("unable to create htlc sender script: %v", err)
+		}
+		htlcPkScript, err = WitnessScriptHash(htlcWitnessScript)
+		if err != nil {
+			t.Fatalf("unable to create p2wsh htlc script: %v", err)
+		}
+
+		// This will be Alice's commitment transaction. In this
+		// scenario Alice is sending an HTLC to a node she has a path
+		// to (could be Bob, could be multiple hops down, it doesn't
+		// really matter).
+		htlcOutput = &wire.TxOut{
+			Value:    int64(paymentAmt),
+			PkScript: htlcPkScript,
+		}
+		senderCommitTx = wire.NewMsgTx(2)
+		senderCommitTx.AddTxIn(fakeFundingTxIn)
+		senderCommitTx.AddTxOut(htlcOutput)
+	}
+
+	// genSweepTx generates a sweep of the senderCommitTx.
+	genSweepTx := func() {
+		prevOut := &wire.OutPoint{
+			Hash:  senderCommitTx.TxHash(),
+			Index: 0,
+		}
+
+		sweepTx = wire.NewMsgTx(2)
+
+		sweepTx.AddTxIn(wire.NewTxIn(prevOut, nil, nil))
+
+		sweepTx.AddTxOut(
+			&wire.TxOut{
+				PkScript: []byte("doesn't matter"),
+				Value:    1 * 10e8,
+			},
+		)
+
+		sweepTxSigHashes = txscript.NewTxSigHashes(sweepTx)
+
 		// We'll also generate a signature on the sweep transaction above
 		// that will act as Bob's signature to Alice for the second level HTLC
 		// transaction.
@@ -272,10 +292,11 @@ func TestHTLCSenderSpendValidation(t *testing.T) {
 			SigHashes:     sweepTxSigHashes,
 			InputIndex:    0,
 		}
-	bobRecvrSig, err := bobSigner.SignOutputRaw(sweepTx, &bobSignDesc)
+		bobRecvrSig, err = bobSigner.SignOutputRaw(sweepTx, &bobSignDesc)
 		if err != nil {
 			t.Fatalf("unable to generate alice signature: %v", err)
 		}
+	}
 
 	testCases := []struct {
 		witness func() wire.TxWitness
@@ -285,6 +306,9 @@ func TestHTLCSenderSpendValidation(t *testing.T) {
 			// revoke w/ sig
 			// TODO(roasbeef): test invalid revoke
 			makeWitnessTestCase(t, func() (wire.TxWitness, error) {
+				genCommitTx()
+				genSweepTx()
+
 				signDesc := &SignDescriptor{
 					KeyDesc: keychain.KeyDescriptor{
 						PubKey: bobKeyPub,
@@ -305,6 +329,9 @@ func TestHTLCSenderSpendValidation(t *testing.T) {
 		{
 			// HTLC with invalid preimage size
 			makeWitnessTestCase(t, func() (wire.TxWitness, error) {
+				genCommitTx()
+				genSweepTx()
+
 				signDesc := &SignDescriptor{
 					KeyDesc: keychain.KeyDescriptor{
 						PubKey: bobKeyPub,
@@ -328,6 +355,9 @@ func TestHTLCSenderSpendValidation(t *testing.T) {
 			// HTLC with valid preimage size + sig
 			// TODO(roasbeef): invalid preimage
 			makeWitnessTestCase(t, func() (wire.TxWitness, error) {
+				genCommitTx()
+				genSweepTx()
+
 				signDesc := &SignDescriptor{
 					KeyDesc: keychain.KeyDescriptor{
 						PubKey: bobKeyPub,
@@ -350,6 +380,9 @@ func TestHTLCSenderSpendValidation(t *testing.T) {
 			// output with the second level HTLC timeout
 			// transaction.
 			makeWitnessTestCase(t, func() (wire.TxWitness, error) {
+				genCommitTx()
+				genSweepTx()
+
 				signDesc := &SignDescriptor{
 					KeyDesc: keychain.KeyDescriptor{
 						PubKey: aliceKeyPub,
@@ -441,46 +474,6 @@ func TestHTLCReceiverSpendValidation(t *testing.T) {
 	// be using Alice's base point for the revocation key.
 	revocationKey := DeriveRevocationPubkey(aliceKeyPub, commitPoint)
 
-	// Generate the raw HTLC redemption scripts, and its p2wsh counterpart.
-	htlcWitnessScript, err := ReceiverHTLCScript(cltvTimeout, aliceLocalKey,
-		bobLocalKey, revocationKey, paymentHash[:])
-	if err != nil {
-		t.Fatalf("unable to create htlc sender script: %v", err)
-	}
-	htlcPkScript, err := WitnessScriptHash(htlcWitnessScript)
-	if err != nil {
-		t.Fatalf("unable to create p2wsh htlc script: %v", err)
-	}
-
-	// This will be Bob's commitment transaction. In this scenario Alice is
-	// sending an HTLC to a node she has a path to (could be Bob, could be
-	// multiple hops down, it doesn't really matter).
-	htlcOutput := &wire.TxOut{
-		Value:    int64(paymentAmt),
-		PkScript: htlcWitnessScript,
-	}
-
-	receiverCommitTx := wire.NewMsgTx(2)
-	receiverCommitTx.AddTxIn(fakeFundingTxIn)
-	receiverCommitTx.AddTxOut(htlcOutput)
-
-	prevOut := &wire.OutPoint{
-		Hash:  receiverCommitTx.TxHash(),
-		Index: 0,
-	}
-
-	sweepTx := wire.NewMsgTx(2)
-	sweepTx.AddTxIn(&wire.TxIn{
-		PreviousOutPoint: *prevOut,
-	})
-	sweepTx.AddTxOut(
-		&wire.TxOut{
-			PkScript: []byte("doesn't matter"),
-			Value:    1 * 10e8,
-		},
-	)
-	sweepTxSigHashes := txscript.NewTxSigHashes(sweepTx)
-
 	bobCommitTweak := SingleTweakBytes(commitPoint, bobKeyPub)
 	aliceCommitTweak := SingleTweakBytes(commitPoint, aliceKeyPub)
 
@@ -490,6 +483,61 @@ func TestHTLCReceiverSpendValidation(t *testing.T) {
 	bobSigner := &MockSigner{Privkeys: []*btcec.PrivateKey{bobKeyPriv}}
 	aliceSigner := &MockSigner{Privkeys: []*btcec.PrivateKey{aliceKeyPriv}}
 
+	var (
+		htlcWitnessScript, htlcPkScript []byte
+		htlcOutput                      *wire.TxOut
+		receiverCommitTx, sweepTx       *wire.MsgTx
+		sweepTxSigHashes                *txscript.TxSigHashes
+		aliceSenderSig                  []byte
+	)
+
+	genCommitTx := func() {
+		// Generate the raw HTLC redemption scripts, and its p2wsh
+		// counterpart.
+		htlcWitnessScript, err = ReceiverHTLCScript(
+			cltvTimeout, aliceLocalKey, bobLocalKey, revocationKey,
+			paymentHash[:],
+		)
+		if err != nil {
+			t.Fatalf("unable to create htlc sender script: %v", err)
+		}
+		htlcPkScript, err = WitnessScriptHash(htlcWitnessScript)
+		if err != nil {
+			t.Fatalf("unable to create p2wsh htlc script: %v", err)
+		}
+
+		// This will be Bob's commitment transaction. In this scenario Alice is
+		// sending an HTLC to a node she has a path to (could be Bob, could be
+		// multiple hops down, it doesn't really matter).
+		htlcOutput = &wire.TxOut{
+			Value:    int64(paymentAmt),
+			PkScript: htlcWitnessScript,
+		}
+
+		receiverCommitTx = wire.NewMsgTx(2)
+		receiverCommitTx.AddTxIn(fakeFundingTxIn)
+		receiverCommitTx.AddTxOut(htlcOutput)
+	}
+
+	genSweepTx := func() {
+		prevOut := &wire.OutPoint{
+			Hash:  receiverCommitTx.TxHash(),
+			Index: 0,
+		}
+
+		sweepTx = wire.NewMsgTx(2)
+		sweepTx.AddTxIn(&wire.TxIn{
+			PreviousOutPoint: *prevOut,
+		})
+
+		sweepTx.AddTxOut(
+			&wire.TxOut{
+				PkScript: []byte("doesn't matter"),
+				Value:    1 * 10e8,
+			},
+		)
+		sweepTxSigHashes = txscript.NewTxSigHashes(sweepTx)
+
 		// We'll also generate a signature on the sweep transaction above
 		// that will act as Alice's signature to Bob for the second level HTLC
 		// transaction.
@@ -504,10 +552,11 @@ func TestHTLCReceiverSpendValidation(t *testing.T) {
 			SigHashes:     sweepTxSigHashes,
 			InputIndex:    0,
 		}
-	aliceSenderSig, err := aliceSigner.SignOutputRaw(sweepTx, &aliceSignDesc)
+		aliceSenderSig, err = aliceSigner.SignOutputRaw(sweepTx, &aliceSignDesc)
 		if err != nil {
 			t.Fatalf("unable to generate alice signature: %v", err)
 		}
+	}
 
 	// TODO(roasbeef): modify valid to check precise script errors?
 	testCases := []struct {
@@ -517,6 +566,9 @@ func TestHTLCReceiverSpendValidation(t *testing.T) {
 		{
 			// HTLC redemption w/ invalid preimage size
 			makeWitnessTestCase(t, func() (wire.TxWitness, error) {
+				genCommitTx()
+				genSweepTx()
+
 				signDesc := &SignDescriptor{
 					KeyDesc: keychain.KeyDescriptor{
 						PubKey: bobKeyPub,
@@ -539,6 +591,9 @@ func TestHTLCReceiverSpendValidation(t *testing.T) {
 		{
 			// HTLC redemption w/ valid preimage size
 			makeWitnessTestCase(t, func() (wire.TxWitness, error) {
+				genCommitTx()
+				genSweepTx()
+
 				signDesc := &SignDescriptor{
 					KeyDesc: keychain.KeyDescriptor{
 						PubKey: bobKeyPub,
@@ -560,6 +615,9 @@ func TestHTLCReceiverSpendValidation(t *testing.T) {
 		{
 			// revoke w/ sig
 			makeWitnessTestCase(t, func() (wire.TxWitness, error) {
+				genCommitTx()
+				genSweepTx()
+
 				signDesc := &SignDescriptor{
 					KeyDesc: keychain.KeyDescriptor{
 						PubKey: aliceKeyPub,
@@ -580,6 +638,9 @@ func TestHTLCReceiverSpendValidation(t *testing.T) {
 		{
 			// refund w/ invalid lock time
 			makeWitnessTestCase(t, func() (wire.TxWitness, error) {
+				genCommitTx()
+				genSweepTx()
+
 				signDesc := &SignDescriptor{
 					KeyDesc: keychain.KeyDescriptor{
 						PubKey: aliceKeyPub,
@@ -600,6 +661,9 @@ func TestHTLCReceiverSpendValidation(t *testing.T) {
 		{
 			// refund w/ valid lock time
 			makeWitnessTestCase(t, func() (wire.TxWitness, error) {
+				genCommitTx()
+				genSweepTx()
+
 				signDesc := &SignDescriptor{
 					KeyDesc: keychain.KeyDescriptor{
 						PubKey: aliceKeyPub,