store: Show error message when replacing event queue

Fixes: zulip#555

Signed-off-by: Zixuan James Li <[email protected]>

Author: PIG208

assets/l10n/app_en.arb

@@ -172,6 +172,11 @@
       "error": {"type": "String", "example": "Invalid format"}
     }
   },
+  "errorReconnectingToServer": "Reconnecting to {serverUrl}…",
+  "@errorReconnectingToServer": {
+    "serverUrl": {"type": "String", "example": "http://example.com/"},
+    "description": "Message when reconnecting to the server."
+  },
   "errorSharingFailed": "Sharing failed",
   "@errorSharingFailed": {
     "description": "Error message when sharing a message failed."

lib/model/store.dart

@@ -959,6 +959,7 @@ class UpdateMachine {
         switch (e) {
           case ZulipApiException(code: 'BAD_EVENT_QUEUE_ID'):
             assert(debugLog('Lost event queue for $store.  Replacing…'));
+            reportErrorToUserBriefly(localizations.errorReconnectingToServer(serverUrl));
             // This disposes the store, which disposes this update machine.
             await store._globalStore._reloadPerAccount(store.accountId);
             debugLog('… Event queue replaced.');

test/model/store_test.dart

@@ -561,6 +561,9 @@ void main() {
     }
 
     test('handles expired queue', () => awaitFakeAsync((async) async {
+      reportErrorToUserBriefly = logAndReportErrorToUserBriefly;
+      addTearDown(() => reportErrorToUserBriefly = defaultReportErrorToUserBriefly);
+
       await prepareStore();
       updateMachine.debugPauseLoop();
       updateMachine.poll();
@@ -574,7 +577,10 @@ void main() {
       });
       updateMachine.debugAdvanceLoop();
       async.flushMicrotasks();
+      check(lastReportedError).isNull();
       await Future<void>.delayed(Duration.zero);
+      check(takeLastReportedError()).isNotNull()
+        .contains('Reconnecting to ${eg.realmUrl.origin}…');
       check(store).isLoading.isTrue();
 
       // The global store has a new store.