[battery] Port battery to use platform interface (#2980)

Author: yash1200

packages/battery/battery/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 1.0.5
+
+* Ported to use platform interface.
+
 ## 1.0.4+1
 
 * Moved everything from battery to battery/battery

packages/battery/battery/lib/battery.dart

@@ -4,72 +4,19 @@
 
 import 'dart:async';
 
-import 'package:flutter/services.dart';
-import 'package:meta/meta.dart' show visibleForTesting;
+import 'package:battery_platform_interface/battery_platform_interface.dart';
 
-/// Indicates the current battery state.
-enum BatteryState {
-  /// The battery is completely full of energy.
-  full,
-
-  /// The battery is currently storing energy.
-  charging,
-
-  /// The battery is currently losing energy.
-  discharging
-}
+export 'package:battery_platform_interface/battery_platform_interface.dart'
+    show BatteryState;
 
 /// API for accessing information about the battery of the device the Flutter
 /// app is currently running on.
 class Battery {
-  /// Initializes the plugin and starts listening for potential platform events.
-  factory Battery() {
-    if (_instance == null) {
-      final MethodChannel methodChannel =
-          const MethodChannel('plugins.flutter.io/battery');
-      final EventChannel eventChannel =
-          const EventChannel('plugins.flutter.io/charging');
-      _instance = Battery.private(methodChannel, eventChannel);
-    }
-    return _instance;
-  }
-
-  /// This constructor is only used for testing and shouldn't be accessed by
-  /// users of the plugin. It may break or change at any time.
-  @visibleForTesting
-  Battery.private(this._methodChannel, this._eventChannel);
-
-  static Battery _instance;
-
-  final MethodChannel _methodChannel;
-  final EventChannel _eventChannel;
-  Stream<BatteryState> _onBatteryStateChanged;
-
   /// Returns the current battery level in percent.
-  Future<int> get batteryLevel => _methodChannel
-      .invokeMethod<int>('getBatteryLevel')
-      .then<int>((dynamic result) => result);
+  Future<int> get batteryLevel async =>
+      await BatteryPlatform.instance.batteryLevel();
 
   /// Fires whenever the battery state changes.
-  Stream<BatteryState> get onBatteryStateChanged {
-    if (_onBatteryStateChanged == null) {
-      _onBatteryStateChanged = _eventChannel
-          .receiveBroadcastStream()
-          .map((dynamic event) => _parseBatteryState(event));
-    }
-    return _onBatteryStateChanged;
-  }
-}
-
-BatteryState _parseBatteryState(String state) {
-  switch (state) {
-    case 'full':
-      return BatteryState.full;
-    case 'charging':
-      return BatteryState.charging;
-    case 'discharging':
-      return BatteryState.discharging;
-    default:
-      throw ArgumentError('$state is not a valid BatteryState.');
-  }
+  Stream<BatteryState> get onBatteryStateChanged =>
+      BatteryPlatform.instance.onBatteryStateChanged();
 }

packages/battery/battery/pubspec.yaml

@@ -2,7 +2,7 @@ name: battery
 description: Flutter plugin for accessing information about the battery state
   (full, charging, discharging) on Android and iOS.
 homepage: https://github.com/flutter/plugins/tree/master/packages/battery/battery
-version: 1.0.4+1
+version: 1.0.5
 
 flutter:
   plugin:
@@ -17,13 +17,15 @@ dependencies:
   flutter:
     sdk: flutter
   meta: ^1.0.5
+  battery_platform_interface: ^1.0.0
 
 dev_dependencies:
   async: ^2.0.8
   test: ^1.3.0
-  mockito: 3.0.0
+  mockito: ^4.1.1
   flutter_test:
     sdk: flutter
+  plugin_platform_interface: ^1.0.0
   integration_test:
     path: ../../integration_test
   pedantic: ^1.8.0

packages/battery/battery/test/battery_test.dart

@@ -4,68 +4,42 @@
 
 import 'dart:async';
 
-import 'package:async/async.dart';
-import 'package:flutter/services.dart';
+import 'package:battery_platform_interface/battery_platform_interface.dart';
+import 'package:plugin_platform_interface/plugin_platform_interface.dart';
 import 'package:test/test.dart';
 import 'package:battery/battery.dart';
 import 'package:mockito/mockito.dart';
 
 void main() {
-  MockMethodChannel methodChannel;
-  MockEventChannel eventChannel;
-  Battery battery;
-
-  setUp(() {
-    methodChannel = MockMethodChannel();
-    eventChannel = MockEventChannel();
-    battery = Battery.private(methodChannel, eventChannel);
-  });
-
-  test('batteryLevel', () async {
-    when(methodChannel.invokeMethod<int>('getBatteryLevel'))
-        .thenAnswer((Invocation invoke) => Future<int>.value(42));
-    expect(await battery.batteryLevel, 42);
-  });
-
-  group('battery state', () {
-    StreamController<String> controller;
-
-    setUp(() {
-      controller = StreamController<String>();
-      when(eventChannel.receiveBroadcastStream())
-          .thenAnswer((Invocation invoke) => controller.stream);
-    });
-
-    tearDown(() {
-      controller.close();
+  group('battery', () {
+    Battery battery;
+    MockBatteryPlatform fakePlatform;
+    setUp(() async {
+      fakePlatform = MockBatteryPlatform();
+      BatteryPlatform.instance = fakePlatform;
+      battery = Battery();
     });
-
-    test('calls receiveBroadcastStream once', () {
-      battery.onBatteryStateChanged;
-      battery.onBatteryStateChanged;
-      battery.onBatteryStateChanged;
-      verify(eventChannel.receiveBroadcastStream()).called(1);
+    test('batteryLevel', () async {
+      int result = await battery.batteryLevel;
+      expect(result, 42);
     });
-
-    test('receive values', () async {
-      final StreamQueue<BatteryState> queue =
-          StreamQueue<BatteryState>(battery.onBatteryStateChanged);
-
-      controller.add("full");
-      expect(await queue.next, BatteryState.full);
-
-      controller.add("discharging");
-      expect(await queue.next, BatteryState.discharging);
-
-      controller.add("charging");
-      expect(await queue.next, BatteryState.charging);
-
-      controller.add("illegal");
-      expect(queue.next, throwsArgumentError);
+    test('onBatteryStateChanged', () async {
+      BatteryState result = await battery.onBatteryStateChanged.first;
+      expect(result, BatteryState.full);
     });
   });
 }
 
-class MockMethodChannel extends Mock implements MethodChannel {}
-
-class MockEventChannel extends Mock implements EventChannel {}
+class MockBatteryPlatform extends Mock
+    with MockPlatformInterfaceMixin
+    implements BatteryPlatform {
+  Future<int> batteryLevel() async {
+    return 42;
+  }
+
+  Stream<BatteryState> onBatteryStateChanged() {
+    StreamController<BatteryState> result = StreamController<BatteryState>();
+    result.add(BatteryState.full);
+    return result.stream;
+  }
+}