Merge pull request #3705 from joostjager/payment-fail-log

routing+htlcswitch: improve failed payment logging

htlcswitch/failure.go

@@ -30,10 +30,14 @@ type ForwardingError struct {
 // returned.
 func (f *ForwardingError) Error() string {
 	if f.ExtraMsg == "" {
-		return fmt.Sprintf("%v", f.FailureMessage)
+		return fmt.Sprintf(
+			"%v@%v", f.FailureMessage, f.FailureSourceIdx,
+		)
 	}
 
-	return fmt.Sprintf("%v: %v", f.FailureMessage, f.ExtraMsg)
+	return fmt.Sprintf(
+		"%v@%v: %v", f.FailureMessage, f.FailureSourceIdx, f.ExtraMsg,
+	)
 }
 
 // ErrorDecrypter is an interface that is used to decrypt the onion encrypted

htlcswitch/link_test.go

@@ -1248,8 +1248,14 @@ func TestChannelLinkMultiHopUnknownNextHop(t *testing.T) {
 		totalTimelock).Wait(30 * time.Second)
 	if err == nil {
 		t.Fatal("error haven't been received")
-	} else if err.Error() != lnwire.CodeUnknownNextPeer.String() {
-		t.Fatalf("wrong error have been received: %v", err)
+	}
+	fErr, ok := err.(*ForwardingError)
+	if !ok {
+		t.Fatalf("expected ForwardingError")
+	}
+	if _, ok = fErr.FailureMessage.(*lnwire.FailUnknownNextPeer); !ok {
+		t.Fatalf("wrong error has been received: %T",
+			fErr.FailureMessage)
 	}
 
 	// Wait for Alice to receive the revocation.