htlcswitch/test: assert on replied failure message

htlcswitch/mock.go

@@ -334,6 +334,7 @@ var _ hop.Iterator = (*mockHopIterator)(nil)
 // encodes the failure and do not makes any onion obfuscation.
 type mockObfuscator struct {
 	ogPacket *sphinx.OnionPacket
+	failure  lnwire.FailureMessage
 }
 
 // NewMockObfuscator initializes a dummy mockObfuscator used for testing.
@@ -366,6 +367,8 @@ func (o *mockObfuscator) Reextract(
 func (o *mockObfuscator) EncryptFirstHop(failure lnwire.FailureMessage) (
 	lnwire.OpaqueReason, error) {
 
+	o.failure = failure
+
 	var b bytes.Buffer
 	if err := lnwire.EncodeFailure(&b, failure, 0); err != nil {
 		return nil, err

htlcswitch/switch_test.go

@@ -1336,6 +1336,7 @@ func TestSkipIneligibleLinksMultiHopForward(t *testing.T) {
 	// Alice.
 	preimage := [sha256.Size]byte{1}
 	rhash := fastsha256.Sum256(preimage[:])
+	obfuscator := NewMockObfuscator()
 	packet = &htlcPacket{
 		incomingChanID: aliceChannelLink.ShortChanID(),
 		incomingHTLCID: 0,
@@ -1344,7 +1345,7 @@ func TestSkipIneligibleLinksMultiHopForward(t *testing.T) {
 			PaymentHash: rhash,
 			Amount:      1,
 		},
-		obfuscator: NewMockObfuscator(),
+		obfuscator: obfuscator,
 	}
 
 	// The request to forward should fail as
@@ -1353,6 +1354,11 @@ func TestSkipIneligibleLinksMultiHopForward(t *testing.T) {
 		t.Fatalf("forwarding should have failed due to inactive link")
 	}
 
+	failure := obfuscator.(*mockObfuscator).failure
+	if _, ok := failure.(*lnwire.FailTemporaryChannelFailure); !ok {
+		t.Fatalf("unexpected failure %T", failure)
+	}
+
 	if s.circuits.NumOpen() != 0 {
 		t.Fatal("wrong amount of circuits")
 	}