snapshot of https://github.com/flutter/samples.git (main, 2026-09-16; blobs > 131072B omitted)

testing_app/lib/main.dart

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+// Copyright 2020 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+import 'package:provider/provider.dart';
+import 'package:testing_app/models/favorites.dart';
+import 'package:testing_app/screens/favorites.dart';
+import 'package:testing_app/screens/home.dart';
+
+void main() {
+  runApp(const TestingApp());
+}
+
+GoRouter router() {
+  return GoRouter(
+    routes: [
+      GoRoute(
+        path: HomePage.routeName,
+        builder: (context, state) => const HomePage(),
+        routes: [
+          GoRoute(
+            path: FavoritesPage.routeName,
+            builder: (context, state) => const FavoritesPage(),
+          ),
+        ],
+      ),
+    ],
+  );
+}
+
+class TestingApp extends StatelessWidget {
+  const TestingApp({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return ChangeNotifierProvider<Favorites>(
+      create: (context) => Favorites(),
+      child: MaterialApp.router(
+        title: 'Testing Sample',
+        theme: ThemeData(
+          colorSchemeSeed: Colors.blue,
+          visualDensity: VisualDensity.adaptivePlatformDensity,
+        ),
+        routerConfig: router(),
+      ),
+    );
+  }
+}

testing_app/lib/models/favorites.dart

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+// Copyright 2020 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+
+/// The [Favorites] class holds a list of favorite items saved by the user.
+class Favorites extends ChangeNotifier {
+  final List<int> _favoriteItems = [];
+
+  List<int> get items => _favoriteItems;
+
+  void add(int itemNo) {
+    _favoriteItems.add(itemNo);
+    notifyListeners();
+  }
+
+  void remove(int itemNo) {
+    _favoriteItems.remove(itemNo);
+    notifyListeners();
+  }
+}

testing_app/lib/screens/favorites.dart

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+// Copyright 2020 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
+import 'package:testing_app/models/favorites.dart';
+
+class FavoritesPage extends StatelessWidget {
+  static const routeName = 'favorites_page';
+  static const fullPath = '/$routeName';
+
+  const FavoritesPage({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(title: const Text('Favorites')),
+      body: Consumer<Favorites>(
+        builder: (context, value, child) => value.items.isNotEmpty
+            ? ListView.builder(
+                itemCount: value.items.length,
+                padding: const EdgeInsets.symmetric(vertical: 16),
+                itemBuilder: (context, index) =>
+                    FavoriteItemTile(value.items[index]),
+              )
+            : const Center(child: Text('No favorites added.')),
+      ),
+    );
+  }
+}
+
+class FavoriteItemTile extends StatelessWidget {
+  final int itemNo;
+
+  const FavoriteItemTile(this.itemNo, {super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Padding(
+      padding: const EdgeInsets.all(8.0),
+      child: ListTile(
+        leading: CircleAvatar(
+          backgroundColor: Colors.primaries[itemNo % Colors.primaries.length],
+        ),
+        title: Text('Item $itemNo', key: Key('favorites_text_$itemNo')),
+        trailing: IconButton(
+          key: Key('remove_icon_$itemNo'),
+          icon: const Icon(Icons.close),
+          onPressed: () {
+            context.read<Favorites>().remove(itemNo);
+            ScaffoldMessenger.of(context).showSnackBar(
+              const SnackBar(
+                content: Text('Removed from favorites.'),
+                duration: Duration(seconds: 1),
+              ),
+            );
+          },
+        ),
+      ),
+    );
+  }
+}

testing_app/lib/screens/home.dart

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+// Copyright 2020 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+import 'package:provider/provider.dart';
+import 'package:testing_app/models/favorites.dart';
+import 'package:testing_app/screens/favorites.dart';
+
+class HomePage extends StatelessWidget {
+  static const routeName = '/';
+
+  const HomePage({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: const Text('Testing Sample'),
+        actions: [
+          TextButton.icon(
+            onPressed: () {
+              context.go(FavoritesPage.fullPath);
+            },
+            icon: const Icon(Icons.favorite_border),
+            label: const Text('Favorites'),
+          ),
+        ],
+      ),
+      body: ListView.builder(
+        itemCount: 100,
+        controller: ScrollController(),
+        padding: const EdgeInsets.symmetric(vertical: 16),
+        itemBuilder: (context, index) => ItemTile(index),
+      ),
+    );
+  }
+}
+
+class ItemTile extends StatelessWidget {
+  final int itemNo;
+
+  const ItemTile(this.itemNo, {super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    final favoritesList = context.watch<Favorites>();
+
+    return Padding(
+      padding: const EdgeInsets.all(8.0),
+      child: ListTile(
+        leading: CircleAvatar(
+          backgroundColor: Colors.primaries[itemNo % Colors.primaries.length],
+        ),
+        title: Text('Item $itemNo', key: Key('text_$itemNo')),
+        trailing: IconButton(
+          key: Key('icon_$itemNo'),
+          icon: favoritesList.items.contains(itemNo)
+              ? const Icon(Icons.favorite)
+              : const Icon(Icons.favorite_border),
+          onPressed: () {
+            !favoritesList.items.contains(itemNo)
+                ? favoritesList.add(itemNo)
+                : favoritesList.remove(itemNo);
+            ScaffoldMessenger.of(context).showSnackBar(
+              SnackBar(
+                content: Text(
+                  favoritesList.items.contains(itemNo)
+                      ? 'Added to favorites.'
+                      : 'Removed from favorites.',
+                ),
+                duration: const Duration(seconds: 1),
+              ),
+            );
+          },
+        ),
+      ),
+    );
+  }
+}