Migrate tests to package:web, make the extension testable.

packages/shared_preferences/shared_preferences_web/example/integration_test/shared_preferences_web_test.dart

@@ -2,14 +2,15 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:html' as html;
-
 import 'package:flutter_test/flutter_test.dart';
 import 'package:integration_test/integration_test.dart';
 import 'package:shared_preferences_platform_interface/method_channel_shared_preferences.dart';
 import 'package:shared_preferences_platform_interface/shared_preferences_platform_interface.dart';
 import 'package:shared_preferences_platform_interface/types.dart';
 import 'package:shared_preferences_web/shared_preferences_web.dart';
+import 'package:shared_preferences_web/src/keys_extension.dart';
+
+import 'package:web/helpers.dart' as html;
 
 const Map<String, dynamic> kTestValues = <String, dynamic>{
   'flutter.String': 'hello world',
@@ -114,6 +115,15 @@ void main() {
         allTestValues['flutter.StringList']!);
   }
 
+  testWidgets('keys', (WidgetTester _) async {
+    await addData();
+    final Iterable<String> keys = html.window.localStorage.keys;
+    final Iterable<String> expectedKeys = allTestValues.keys;
+
+    expect(keys, hasLength(expectedKeys.length));
+    expect(keys, containsAll(expectedKeys));
+  });
+
   testWidgets('clear', (WidgetTester _) async {
     await addData();
     await preferences.clear();

packages/shared_preferences/shared_preferences_web/example/pubspec.yaml

@@ -2,15 +2,16 @@ name: shared_preferences_web_integration_tests
 publish_to: none
 
 environment:
-  sdk: ">=3.0.0 <4.0.0"
-  flutter: ">=3.10.0"
+  sdk: ">=3.2.0 <4.0.0"
+  flutter: ">=3.16.0"
 
 dependencies:
   flutter:
     sdk: flutter
   shared_preferences_platform_interface: ^2.3.0
   shared_preferences_web:
     path: ../
+  web: '>=0.3.0 <0.5.0'
 
 dev_dependencies:
   flutter_test:

packages/shared_preferences/shared_preferences_web/lib/shared_preferences_web.dart

@@ -10,6 +10,8 @@ import 'package:shared_preferences_platform_interface/shared_preferences_platfor
 import 'package:shared_preferences_platform_interface/types.dart';
 import 'package:web/web.dart' as html;
 
+import 'src/keys_extension.dart';
+
 /// The web implementation of [SharedPreferencesStorePlatform].
 ///
 /// This class implements the `package:shared_preferences` functionality for the web.
@@ -111,9 +113,3 @@ class SharedPreferencesPlugin extends SharedPreferencesStorePlatform {
     return decodedValue!;
   }
 }
-
-extension on html.Storage {
-  List<String> get keys {
-    return <String>[for (int i = 0; i < length; i++) key(i)!];
-  }
-}

packages/shared_preferences/shared_preferences_web/lib/src/keys_extension.dart

@@ -0,0 +1,13 @@
+// Copyright 2013 The Flutter Authors. 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:web/web.dart' as html;
+
+/// An extension on [html.Storage] that adds a convenience [keys] getter.
+extension KeysExtension on html.Storage {
+  /// Gets all the [keys] set in this [html.Storage].
+  List<String> get keys {
+    return <String>[for (int i = 0; i < length; i++) key(i)!];
+  }
+}