avatar: Show placeholder on image load error

Author: vinodsingh-dev-gsoc

lib/widgets/user.dart

@@ -1,5 +1,4 @@
 import 'package:flutter/material.dart';
-
 import '../api/model/model.dart';
 import '../model/avatar_url.dart';
 import '../model/binding.dart';
@@ -90,6 +89,9 @@ class AvatarImage extends StatelessWidget {
       avatarUrl.get(physicalSize),
       filterQuality: FilterQuality.medium,
       fit: BoxFit.cover,
+      errorBuilder: (context, error, stackTrace) {
+        return _AvatarPlaceholder(size: size);
+      },
     );
   }
 }

test/widgets/user_test.dart

@@ -1,18 +1,26 @@
 import 'package:checks/checks.dart';
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
-import 'package:flutter/rendering.dart';
+import 'package:zulip/widgets/icons.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:zulip/model/store.dart';
 import 'package:zulip/widgets/content.dart';
 import 'package:zulip/widgets/store.dart';
 import 'package:zulip/widgets/user.dart';
-
+import 'dart:io';
 import '../example_data.dart' as eg;
 import '../model/binding.dart';
 import '../model/test_store.dart';
 import '../stdlib_checks.dart';
 import '../test_images.dart';
+import 'test_app.dart';
+
+class MockHttpClient extends Fake implements HttpClient {
+  @override
+  Future<HttpClientRequest> getUrl(Uri url) async {
+    throw const SocketException('test error');
+  }
+}
 
 void main() {
   TestZulipBinding.ensureInitialized();
@@ -78,5 +86,28 @@ void main() {
       check(await actualUrl(tester, avatarUrl)).isNull();
       debugNetworkImageHttpClientProvider = null;
     });
+
+    testWidgets('shows placeholder when image URL gives error', (WidgetTester tester) async {
+      await HttpOverrides.runZoned(() async {
+        addTearDown(testBinding.reset);
+        await testBinding.globalStore.add(eg.selfAccount, eg.initialSnapshot());
+        final store = await testBinding.globalStore.perAccount(eg.selfAccount.id);
+        final user = eg.user(avatarUrl: 'https://zulip.com/avatar.png');
+        await store.addUser(user);
+
+        await tester.pumpWidget(
+          TestZulipApp(
+            accountId: eg.selfAccount.id,
+            child: AvatarImage(userId: user.userId, size: 32),
+          ),
+        );
+        await tester.pump(); // Image provider is created
+        await tester.pump(); // Image fails to load
+        expect(find.byIcon(ZulipIcons.person), findsOneWidget);
+
+        expect(find.byType(DecoratedBox), findsOneWidget);
+
+      }, createHttpClient: (context) => MockHttpClient());
+    });
   });
 }