store: Report non-transient polling errors.

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

Author: PIG208

assets/l10n/app_en.arb

@@ -160,6 +160,13 @@
       "message": {"type": "String", "example": "Invalid format"}
     }
   },
+  "errorLoadingServerData": "Error loading server data. Will retry:\n\n{error}",
+  "@errorLoadingServerData": {
+    "description": "Dialog message for a generic unknown error.",
+    "placeholders": {
+      "error": {"type": "String", "example": "Invalid format"}
+    }
+  },
   "errorSharingFailed": "Sharing failed",
   "@errorSharingFailed": {
     "description": "Error message when sharing a message failed."

lib/model/store.dart

@@ -20,6 +20,7 @@ import '../log.dart';
 import '../notifications/receive.dart';
 import 'autocomplete.dart';
 import 'database.dart';
+import 'localizations.dart';
 import 'message.dart';
 import 'message_list.dart';
 import 'recent_dm_conversations.dart';
@@ -782,6 +783,7 @@ class UpdateMachine {
           queueId: queueId, lastEventId: lastEventId);
       } catch (e) {
         store.isLoading = true;
+        final localizations = GlobalLocalizations.zulipLocalizations;
         switch (e) {
           case ZulipApiException(code: 'BAD_EVENT_QUEUE_ID'):
             assert(debugLog('Lost event queue for $store.  Replacing…'));
@@ -802,7 +804,9 @@ class UpdateMachine {
           default:
             assert(debugLog('Error polling event queue for $store: $e\n'
                 'Backing off and retrying even though may be hopeless…'));
-            // TODO tell user on non-transient error in polling
+            // TODO(#186): Handle unrecoverable failures
+            reportErrorToUserInDialog(
+              localizations.errorLoadingServerData(e.toString()));
             await (backoffMachine ??= BackoffMachine()).wait();
             assert(debugLog('… Backoff wait complete, retrying poll.'));
             continue;

test/model/store_test.dart

@@ -8,6 +8,7 @@ import 'package:zulip/api/model/events.dart';
 import 'package:zulip/api/model/model.dart';
 import 'package:zulip/api/route/events.dart';
 import 'package:zulip/api/route/messages.dart';
+import 'package:zulip/log.dart';
 import 'package:zulip/model/store.dart';
 import 'package:zulip/notifications/receive.dart';
 
@@ -427,7 +428,9 @@ void main() {
       check(store.userSettings!.twentyFourHourTime).isTrue();
     }));
 
-    void checkRetry(String description, void Function() prepareError) {
+    void checkRetry(String description, void Function() prepareError, {
+      String? errorMessage,
+    }) {
       test(description, () {
         awaitFakeAsync((async) async {
           await prepareStore(lastEventId: 1);
@@ -438,7 +441,13 @@ void main() {
           // Make the request, inducing an error in it.
           prepareError();
           updateMachine.debugAdvanceLoop();
+          check(debugLastReportedError).isNull();
           async.elapse(Duration.zero);
+          if (errorMessage == null) {
+            check(takeLastReportedError()).isNull();
+          } else {
+            check(takeLastReportedError()).isNotNull().contains(errorMessage);
+          }
           checkLastRequest(lastEventId: 1);
           check(store).isLoading.isTrue();
 
@@ -470,10 +479,12 @@ void main() {
 
       checkRetry('retries on ZulipApiException',
         () => connection.prepare(httpStatus: 400, json: {
-          'result': 'error', 'code': 'BAD_REQUEST', 'msg': 'Bad request'}));
+          'result': 'error', 'code': 'BAD_REQUEST', 'msg': 'Bad request'}),
+        errorMessage: 'Error loading server data. Will retry');
 
       checkRetry('retries on MalformedServerResponseException',
-        () => connection.prepare(httpStatus: 200, body: 'nonsense'));
+        () => connection.prepare(httpStatus: 200, body: 'nonsense'),
+        errorMessage: 'Error loading server data. Will retry');
     });
   });