Implement shared_preferences on top of platform interface

.gitignore

@@ -30,6 +30,7 @@ keystore.properties
 gradlew
 gradlew.bat
 gradle-wrapper.jar
+.flutter-plugins-dependencies
 *.iml
 
 GeneratedPluginRegistrant.h

packages/shared_preferences/shared_preferences/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 0.5.4+8
+
+* Switch `package:shared_preferences` to `package:shared_preferences_platform_interface`.
+  No code changes are necessary in Flutter apps. This is not a breaking change.
+
 ## 0.5.4+7
 
 * Restructure the project for Web support.

packages/shared_preferences/shared_preferences/example/lib/main.dart

@@ -67,13 +67,14 @@ class SharedPreferencesDemoState extends State<SharedPreferencesDemo> {
                   case ConnectionState.waiting:
                     return const CircularProgressIndicator();
                   default:
-                    if (snapshot.hasError)
+                    if (snapshot.hasError) {
                       return Text('Error: ${snapshot.error}');
-                    else
+                    } else {
                       return Text(
                         'Button tapped ${snapshot.data} time${snapshot.data == 1 ? '' : 's'}.\n\n'
                         'This should persist across restarts.',
                       );
+                    }
                 }
               })),
       floatingActionButton: FloatingActionButton(

packages/shared_preferences/shared_preferences/example/test_driver/shared_preferences_e2e.dart

@@ -63,23 +63,21 @@ void main() {
 
     test('removing', () async {
       const String key = 'testKey';
-      preferences
-        ..setString(key, kTestValues['flutter.String'])
-        ..setBool(key, kTestValues['flutter.bool'])
-        ..setInt(key, kTestValues['flutter.int'])
-        ..setDouble(key, kTestValues['flutter.double'])
-        ..setStringList(key, kTestValues['flutter.List']);
+      await preferences.setString(key, kTestValues['flutter.String']);
+      await preferences.setBool(key, kTestValues['flutter.bool']);
+      await preferences.setInt(key, kTestValues['flutter.int']);
+      await preferences.setDouble(key, kTestValues['flutter.double']);
+      await preferences.setStringList(key, kTestValues['flutter.List']);
       await preferences.remove(key);
       expect(preferences.get('testKey'), isNull);
     });
 
     test('clearing', () async {
-      preferences
-        ..setString('String', kTestValues['flutter.String'])
-        ..setBool('bool', kTestValues['flutter.bool'])
-        ..setInt('int', kTestValues['flutter.int'])
-        ..setDouble('double', kTestValues['flutter.double'])
-        ..setStringList('List', kTestValues['flutter.List']);
+      await preferences.setString('String', kTestValues['flutter.String']);
+      await preferences.setBool('bool', kTestValues['flutter.bool']);
+      await preferences.setInt('int', kTestValues['flutter.int']);
+      await preferences.setDouble('double', kTestValues['flutter.double']);
+      await preferences.setStringList('List', kTestValues['flutter.List']);
       await preferences.clear();
       expect(preferences.getString('String'), null);
       expect(preferences.getBool('bool'), null);

packages/shared_preferences/shared_preferences/example/test_driver/shared_preferences_e2e_test.dart

@@ -10,6 +10,6 @@ Future<void> main() async {
   final FlutterDriver driver = await FlutterDriver.connect();
   final String result =
       await driver.requestData(null, timeout: const Duration(minutes: 1));
-  driver.close();
+  await driver.close();
   exit(result == 'pass' ? 0 : 1);
 }

packages/shared_preferences/shared_preferences/lib/shared_preferences.dart

@@ -4,11 +4,9 @@
 
 import 'dart:async';
 
-import 'package:flutter/services.dart';
 import 'package:meta/meta.dart';
 
-const MethodChannel _kChannel =
-    MethodChannel('plugins.flutter.io/shared_preferences');
+import 'package:shared_preferences_platform_interface/shared_preferences_platform_interface.dart';
 
 /// Wraps NSUserDefaults (on iOS) and SharedPreferences (on Android), providing
 /// a persistent store for simple data.
@@ -20,6 +18,9 @@ class SharedPreferences {
   static const String _prefix = 'flutter.';
   static Completer<SharedPreferences> _completer;
 
+  static SharedPreferencesStorePlatform get _store =>
+      SharedPreferencesStorePlatform.instance;
+
   /// Loads and parses the [SharedPreferences] for this app from disk.
   ///
   /// Because this is reading from disk, it shouldn't be awaited in
@@ -124,37 +125,30 @@ class SharedPreferences {
   Future<bool> remove(String key) => _setValue(null, key, null);
 
   Future<bool> _setValue(String valueType, String key, Object value) {
-    final Map<String, dynamic> params = <String, dynamic>{
-      'key': '$_prefix$key',
-    };
+    final String prefixedKey = '$_prefix$key';
     if (value == null) {
       _preferenceCache.remove(key);
-      return _kChannel
-          .invokeMethod<bool>('remove', params)
-          .then<bool>((dynamic result) => result);
+      return _store.remove(prefixedKey);
     } else {
       if (value is List<String>) {
         // Make a copy of the list so that later mutations won't propagate
         _preferenceCache[key] = value.toList();
       } else {
         _preferenceCache[key] = value;
       }
-      params['value'] = value;
-      return _kChannel
-          .invokeMethod<bool>('set$valueType', params)
-          .then<bool>((dynamic result) => result);
+      return _store.setValue(valueType, prefixedKey, value);
     }
   }
 
   /// Always returns true.
   /// On iOS, synchronize is marked deprecated. On Android, we commit every set.
   @deprecated
-  Future<bool> commit() async => await _kChannel.invokeMethod<bool>('commit');
+  Future<bool> commit() async => true;
 
   /// Completes with true once the user preferences for the app has been cleared.
-  Future<bool> clear() async {
+  Future<bool> clear() {
     _preferenceCache.clear();
-    return await _kChannel.invokeMethod<bool>('clear');
+    return _store.clear();
   }
 
   /// Fetches the latest values from the host platform.
@@ -169,8 +163,7 @@ class SharedPreferences {
   }
 
   static Future<Map<String, Object>> _getSharedPreferencesMap() async {
-    final Map<String, Object> fromSystem =
-        await _kChannel.invokeMapMethod<String, Object>('getAll');
+    final Map<String, Object> fromSystem = await _store.getAll();
     assert(fromSystem != null);
     // Strip the flutter. prefix from the returned preferences.
     final Map<String, Object> preferencesMap = <String, Object>{};
@@ -194,12 +187,8 @@ class SharedPreferences {
       }
       return MapEntry<String, dynamic>(newKey, value);
     });
-    _kChannel.setMockMethodCallHandler((MethodCall methodCall) async {
-      if (methodCall.method == 'getAll') {
-        return newValues;
-      }
-      return null;
-    });
+    SharedPreferencesStorePlatform.instance =
+        InMemorySharedPreferencesStore.withData(newValues);
     _completer = null;
   }
 }

packages/shared_preferences/shared_preferences/pubspec.yaml

@@ -3,7 +3,7 @@ description: Flutter plugin for reading and writing simple key-value pairs.
   Wraps NSUserDefaults on iOS and SharedPreferences on Android.
 author: Flutter Team <flutter-dev@googlegroups.com>
 homepage: https://github.com/flutter/plugins/tree/master/packages/shared_preferences/shared_preferences
-version: 0.5.4+7
+version: 0.5.4+8
 
 flutter:
   plugin:
@@ -15,6 +15,7 @@ dependencies:
   meta: ^1.0.4
   flutter:
     sdk: flutter
+  shared_preferences_platform_interface: ^1.0.0
 
 dev_dependencies:
   flutter_test: