htlcswitch/test: align test invoice cltv expiry

htlcswitch/mock.go

@@ -728,6 +728,8 @@ func newDB() (*channeldb.DB, func(), error) {
 	return cdb, cleanUp, nil
 }
 
+const testInvoiceCltvExpiry = 4
+
 type mockInvoiceRegistry struct {
 	settleChan chan lntypes.Hash
 
@@ -743,7 +745,7 @@ func newMockRegistry(minDelta uint32) *mockInvoiceRegistry {
 	}
 
 	decodeExpiry := func(invoice string) (uint32, error) {
-		return 3, nil
+		return testInvoiceCltvExpiry, nil
 	}
 
 	registry := invoices.NewRegistry(cdb, decodeExpiry)

htlcswitch/test_utils.go

@@ -527,6 +527,12 @@ func generatePaymentWithPreimage(invoiceAmt, htlcAmt lnwire.MilliSatoshi,
 	preimage, rhash [32]byte) (*channeldb.Invoice, *lnwire.UpdateAddHTLC,
 	error) {
 
+	// Create the db invoice. Normally the payment requests needs to be set,
+	// because it is decoded in InvoiceRegistry to obtain the cltv expiry.
+	// But because the mock registry used in tests is mocking the decode
+	// step and always returning the value of testInvoiceCltvExpiry, we
+	// don't need to bother here with creating and signing a payment
+	// request.
 	invoice := &channeldb.Invoice{
 		CreationDate: time.Now(),
 		Terms: channeldb.ContractTerm{
@@ -602,8 +608,6 @@ type threeHopNetwork struct {
 func generateHops(payAmt lnwire.MilliSatoshi, startingHeight uint32,
 	path ...*channelLink) (lnwire.MilliSatoshi, uint32, []ForwardingInfo) {
 
-	lastHop := path[len(path)-1]
-
 	totalTimelock := startingHeight
 	runningAmt := payAmt
 
@@ -620,7 +624,7 @@ func generateHops(payAmt lnwire.MilliSatoshi, startingHeight uint32,
 		// If this is the last, hop, then the time lock will be their
 		// specified delta policy plus our starting height.
 		if i == len(path)-1 {
-			totalTimelock += lastHop.cfg.FwrdingPolicy.TimeLockDelta
+			totalTimelock += testInvoiceCltvExpiry
 			timeLock = totalTimelock
 		} else {
 			// Otherwise, the outgoing time lock should be the