lnwallet: add new htlc set for test vectors

Add a new test htlc set comprised of htlc 1 from the original set and
two new htlcs, 5 and 6, that use the same preimage and have the same
output value (in sats). This htlc set is used in tests that assert the
ordering of htlcs  that have the same preimage and output value.

lnwallet/transactions_test.go

@@ -11,6 +11,7 @@ import (
 	"io/ioutil"
 	"net"
 	"sort"
+	"strings"
 	"testing"
 	"time"
 
@@ -93,41 +94,80 @@ func newTestContext(t *testing.T) *testContext {
 	return tc
 }
 
-var testHtlcs = []struct {
+type htlc struct {
 	incoming bool
 	amount   lnwire.MilliSatoshi
 	expiry   uint32
 	preimage string
-}{
+}
+
+var testHtlcsSet1 = []htlc{
+	// htlc 0.
 	{
 		incoming: true,
 		amount:   1000000,
 		expiry:   500,
-		preimage: "0000000000000000000000000000000000000000000000000000000000000000",
+		preimage: "0000000000000000000000000000000000000000000000000" +
+			"000000000000000",
 	},
+	// htlc 1.
 	{
 		incoming: true,
 		amount:   2000000,
 		expiry:   501,
-		preimage: "0101010101010101010101010101010101010101010101010101010101010101",
+		preimage: "0101010101010101010101010101010101010101010101010" +
+			"101010101010101",
 	},
+	// htlc 2.
 	{
 		incoming: false,
 		amount:   2000000,
 		expiry:   502,
-		preimage: "0202020202020202020202020202020202020202020202020202020202020202",
+		preimage: "0202020202020202020202020202020202020202020202020" +
+			"202020202020202",
 	},
+	// htlc 3.
 	{
 		incoming: false,
 		amount:   3000000,
 		expiry:   503,
-		preimage: "0303030303030303030303030303030303030303030303030303030303030303",
+		preimage: "03030303030303030303030303030303030303030303030303" +
+			"03030303030303",
 	},
+	// htlc 4.
 	{
 		incoming: true,
 		amount:   4000000,
 		expiry:   504,
-		preimage: "0404040404040404040404040404040404040404040404040404040404040404",
+		preimage: "0404040404040404040404040404040404040404040404040" +
+			"404040404040404",
+	},
+}
+
+var testHtlcsSet2 = []htlc{
+	// htlc 1.
+	{
+		incoming: true,
+		amount:   2000000,
+		expiry:   501,
+		preimage: "01010101010101010101010101010101010101010101010101" +
+			"01010101010101",
+	},
+	// htlc 5.
+	{
+		incoming: false,
+		amount:   5000000,
+		expiry:   506,
+		preimage: "05050505050505050505050505050505050505050505050505" +
+			"05050505050505",
+	},
+	// htlc 6.
+	{
+		incoming: false,
+		amount:   5000001,
+		expiry:   505,
+		preimage: "05050505050505050505050505050505050505050505050505" +
+			"05050505050505",
 	},
 }
 
@@ -204,11 +244,11 @@ func TestCommitmentAndHTLCTransactions(t *testing.T) {
 
 // addTestHtlcs adds the test vector htlcs to the update logs of the local and
 // remote node.
-func addTestHtlcs(t *testing.T, remote,
+func addTestHtlcs(t *testing.T, remote, local *LightningChannel,
-	local *LightningChannel) map[[20]byte]lntypes.Preimage {
+	htlcSet []htlc) map[[20]byte]lntypes.Preimage {
 
 	hash160map := make(map[[20]byte]lntypes.Preimage)
-	for _, htlc := range testHtlcs {
+	for _, htlc := range htlcSet {
 		preimage, err := lntypes.MakePreimageFromStr(htlc.preimage)
 		require.NoError(t, err)
 
@@ -255,6 +295,12 @@ func addTestHtlcs(t *testing.T, remote,
 func testVectors(t *testing.T, chanType channeldb.ChannelType, test testCase) {
 	tc := newTestContext(t)
 
+	// Determine which htlc set to use.
+	testHtlcs := testHtlcsSet1
+	if strings.Contains(test.Name, "same amount and preimage") {
+		testHtlcs = testHtlcsSet2
+	}
+
 	// Balances in the test vectors are before subtraction of in-flight
 	// htlcs. Convert to spendable balances.
 	remoteBalance := test.RemoteBalance
@@ -289,7 +335,9 @@ func testVectors(t *testing.T, chanType channeldb.ChannelType, test testCase) {
 	// retrieve the corresponding preimage.
 	var hash160map map[[20]byte]lntypes.Preimage
 	if test.UseTestHtlcs {
-		hash160map = addTestHtlcs(t, remoteChannel, localChannel)
+		hash160map = addTestHtlcs(
+			t, remoteChannel, localChannel, testHtlcs,
+		)
 	}
 
 	// Execute commit dance to arrive at the point where the local node has