Assert that async UIDL processing happens in order (#14643)

Change-Id: Ib2502ad9dc4d28eca41e45efd025478d3f4330a0

1 files changed, 5 insertions, 1 deletions

diff --git a/client/src/com/vaadin/client/ApplicationConnection.java b/client/src/com/vaadin/client/ApplicationConnection.java
index d182706780..cba9639067 100644
--- a/client/src/com/vaadin/client/ApplicationConnection.java
+++ b/client/src/com/vaadin/client/ApplicationConnection.java
@@ -1457,8 +1457,9 @@ public class ApplicationConnection implements HasHandlers {
         VConsole.log("Handling message from server");
         eventBus.fireEvent(new ResponseHandlingStartedEvent(this));
 
+        final int syncId;
         if (json.containsKey(ApplicationConstants.SERVER_SYNC_ID)) {
-            int syncId = json.getInt(ApplicationConstants.SERVER_SYNC_ID);
+            syncId = json.getInt(ApplicationConstants.SERVER_SYNC_ID);
 
             /*
              * Use sync id unless explicitly set as undefined, as is done by
@@ -1471,6 +1472,7 @@ public class ApplicationConnection implements HasHandlers {
                 lastSeenServerSyncId = syncId;
             }
         } else {
+            syncId = -1;
             VConsole.error("Server response didn't contain a sync id. "
                     + "Please verify that the server is up-to-date and that the response data has not been modified in transmission.");
         }
@@ -1541,6 +1543,8 @@ public class ApplicationConnection implements HasHandlers {
         Command c = new Command() {
             @Override
             public void execute() {
+                assert syncId == -1 || syncId == lastSeenServerSyncId;
+
                 handleUIDLDuration.logDuration(" * Loading widgets completed",
                         10);