[sensors] Migrate to null safety

packages/sensors/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.5.0-nullsafety
+
+* Migrate to null safety.
+
 ## 0.4.2+8
 
 * Fix outdated links across a number of markdown files ([#3276](https://github.com/flutter/plugins/pull/3276))

packages/sensors/example/lib/main.dart

@@ -28,7 +28,7 @@ class MyApp extends StatelessWidget {
 }
 
 class MyHomePage extends StatefulWidget {
-  MyHomePage({Key key, this.title}) : super(key: key);
+  MyHomePage({Key? key, required this.title}) : super(key: key);
 
   final String title;
 
@@ -41,21 +41,21 @@ class _MyHomePageState extends State<MyHomePage> {
   static const int _snakeColumns = 20;
   static const double _snakeCellSize = 10.0;
 
-  List<double> _accelerometerValues;
-  List<double> _userAccelerometerValues;
-  List<double> _gyroscopeValues;
+  List<double>? _accelerometerValues;
+  List<double>? _userAccelerometerValues;
+  List<double>? _gyroscopeValues;
   List<StreamSubscription<dynamic>> _streamSubscriptions =
       <StreamSubscription<dynamic>>[];
 
   @override
   Widget build(BuildContext context) {
-    final List<String> accelerometer =
-        _accelerometerValues?.map((double v) => v.toStringAsFixed(1))?.toList();
-    final List<String> gyroscope =
-        _gyroscopeValues?.map((double v) => v.toStringAsFixed(1))?.toList();
-    final List<String> userAccelerometer = _userAccelerometerValues
+    final List<String>? accelerometer =
+        _accelerometerValues?.map((double v) => v.toStringAsFixed(1)).toList();
+    final List<String>? gyroscope =
+        _gyroscopeValues?.map((double v) => v.toStringAsFixed(1)).toList();
+    final List<String>? userAccelerometer = _userAccelerometerValues
         ?.map((double v) => v.toStringAsFixed(1))
-        ?.toList();
+        .toList();
 
     return Scaffold(
       appBar: AppBar(

packages/sensors/example/lib/snake.dart

@@ -61,10 +61,10 @@ class SnakeState extends State<Snake> {
   }
 
   double cellSize;
-  GameState state;
-  AccelerometerEvent acceleration;
-  StreamSubscription<AccelerometerEvent> _streamSubscription;
-  Timer _timer;
+  late final GameState state;
+  AccelerometerEvent? acceleration;
+  late final StreamSubscription<AccelerometerEvent> _streamSubscription;
+  late final Timer _timer;
 
   @override
   Widget build(BuildContext context) {
@@ -96,13 +96,14 @@ class SnakeState extends State<Snake> {
   }
 
   void _step() {
-    final math.Point<int> newDirection = acceleration == null
+    final math.Point<int>? newDirection = acceleration == null
         ? null
-        : acceleration.x.abs() < 1.0 && acceleration.y.abs() < 1.0
+        : acceleration!.x.abs() < 1.0 && acceleration!.y.abs() < 1.0
             ? null
-            : (acceleration.x.abs() < acceleration.y.abs())
-                ? math.Point<int>(0, acceleration.y.sign.toInt())
-                : math.Point<int>(-acceleration.x.sign.toInt(), 0);
+            : (acceleration!.x.abs() < acceleration!.y.abs())
+                ? math.Point<int>(0, acceleration!.y.sign.toInt())
+                : math.Point<int>(-acceleration!.x.sign.toInt(), 0);
+
     state.step(newDirection);
   }
 }
@@ -114,12 +115,12 @@ class GameState {
 
   int rows;
   int columns;
-  int snakeLength;
+  late int snakeLength;
 
   List<math.Point<int>> body = <math.Point<int>>[const math.Point<int>(0, 0)];
   math.Point<int> direction = const math.Point<int>(1, 0);
 
-  void step(math.Point<int> newDirection) {
+  void step(math.Point<int>? newDirection) {
     math.Point<int> next = body.last + direction;
     next = math.Point<int>(next.x % columns, next.y % rows);
 

packages/sensors/example/pubspec.yaml

@@ -12,12 +12,12 @@ dev_dependencies:
     sdk: flutter
   integration_test:
     path: ../../integration_test
-  pedantic: ^1.8.0
+  pedantic: ^1.10.0-nullsafety
 
 flutter:
   uses-material-design: true
 
 environment:
-  sdk: ">=2.0.0-dev.28.0 <3.0.0"
+  sdk: ">=2.12.0-0 <3.0.0"
   flutter: ">=1.9.1+hotfix.2 <2.0.0"
 

packages/sensors/example/test_driver/test/integration_test.dart

@@ -2,6 +2,8 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// @dart = 2.9
+
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';

packages/sensors/integration_test/sensors_test.dart

@@ -2,6 +2,8 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// @dart = 2.9
+
 import 'dart:async';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:sensors/sensors.dart';

packages/sensors/lib/sensors.dart

@@ -121,38 +121,50 @@ GyroscopeEvent _listToGyroscopeEvent(List<double> list) {
   return GyroscopeEvent(list[0], list[1], list[2]);
 }
 
-Stream<AccelerometerEvent> _accelerometerEvents;
-Stream<GyroscopeEvent> _gyroscopeEvents;
-Stream<UserAccelerometerEvent> _userAccelerometerEvents;
+Stream<AccelerometerEvent>? _accelerometerEvents;
+Stream<GyroscopeEvent>? _gyroscopeEvents;
+Stream<UserAccelerometerEvent>? _userAccelerometerEvents;
 
 /// A broadcast stream of events from the device accelerometer.
 Stream<AccelerometerEvent> get accelerometerEvents {
-  if (_accelerometerEvents == null) {
-    _accelerometerEvents = _accelerometerEventChannel
-        .receiveBroadcastStream()
-        .map(
-            (dynamic event) => _listToAccelerometerEvent(event.cast<double>()));
+  Stream<AccelerometerEvent>? accelerometerEvents = _accelerometerEvents;
+  if (accelerometerEvents == null) {
+    accelerometerEvents =
+        _accelerometerEventChannel.receiveBroadcastStream().map(
+              (dynamic event) =>
+                  _listToAccelerometerEvent(event.cast<double>()),
+            );
+    _accelerometerEvents = accelerometerEvents;
   }
-  return _accelerometerEvents;
+
+  return accelerometerEvents;
 }
 
 /// A broadcast stream of events from the device gyroscope.
 Stream<GyroscopeEvent> get gyroscopeEvents {
-  if (_gyroscopeEvents == null) {
-    _gyroscopeEvents = _gyroscopeEventChannel
-        .receiveBroadcastStream()
-        .map((dynamic event) => _listToGyroscopeEvent(event.cast<double>()));
+  Stream<GyroscopeEvent>? gyroscopeEvents = _gyroscopeEvents;
+  if (gyroscopeEvents == null) {
+    gyroscopeEvents = _gyroscopeEventChannel.receiveBroadcastStream().map(
+          (dynamic event) => _listToGyroscopeEvent(event.cast<double>()),
+        );
+    _gyroscopeEvents = gyroscopeEvents;
   }
-  return _gyroscopeEvents;
+
+  return gyroscopeEvents;
 }
 
 /// Events from the device accelerometer with gravity removed.
 Stream<UserAccelerometerEvent> get userAccelerometerEvents {
-  if (_userAccelerometerEvents == null) {
-    _userAccelerometerEvents = _userAccelerometerEventChannel
-        .receiveBroadcastStream()
-        .map((dynamic event) =>
-            _listToUserAccelerometerEvent(event.cast<double>()));
+  Stream<UserAccelerometerEvent>? userAccelerometerEvents =
+      _userAccelerometerEvents;
+  if (userAccelerometerEvents == null) {
+    userAccelerometerEvents =
+        _userAccelerometerEventChannel.receiveBroadcastStream().map(
+              (dynamic event) =>
+                  _listToUserAccelerometerEvent(event.cast<double>()),
+            );
+    _userAccelerometerEvents = userAccelerometerEvents;
   }
-  return _userAccelerometerEvents;
+
+  return userAccelerometerEvents;
 }

packages/sensors/pubspec.yaml

@@ -5,7 +5,7 @@ homepage: https://github.com/flutter/plugins/tree/master/packages/sensors
 # 0.4.y+z is compatible with 1.0.0, if you land a breaking change bump
 # the version to 2.0.0.
 # See more details: https://github.com/flutter/flutter/wiki/Package-migration-to-1.0.0
-version: 0.4.2+8
+version: 0.5.0-nullsafety
 
 flutter:
   plugin:
@@ -21,14 +21,14 @@ dependencies:
     sdk: flutter
 
 dev_dependencies:
-  test: ^1.3.0
+  test: ^1.16.0-nullsafety
   flutter_test:
     sdk: flutter
   integration_test:
     path: ../integration_test
-  mockito: ^4.1.1
-  pedantic: ^1.8.0
+  mockito: ^5.0.0-nullsafety.0
+  pedantic: ^1.10.0-nullsafety
 
 environment:
-  sdk: ">=2.1.0<3.0.0"
+  sdk: ">=2.12.0-0 <3.0.0"
   flutter: ">=1.12.13+hotfix.5"

packages/sensors/test/sensors_test.dart

@@ -52,16 +52,16 @@ void main() {
 void _initializeFakeSensorChannel(String channelName, List<double> sensorData) {
   const StandardMethodCodec standardMethod = StandardMethodCodec();
 
-  void _emitEvent(ByteData event) {
-    ServicesBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
+  void _emitEvent(ByteData? event) {
+    ServicesBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
       channelName,
       event,
-      (ByteData reply) {},
+      (ByteData? reply) {},
     );
   }
 
-  ServicesBinding.instance.defaultBinaryMessenger
-      .setMockMessageHandler(channelName, (ByteData message) async {
+  ServicesBinding.instance!.defaultBinaryMessenger
+      .setMockMessageHandler(channelName, (ByteData? message) async {
     final MethodCall methodCall = standardMethod.decodeMethodCall(message);
     if (methodCall.method == 'listen') {
       _emitEvent(standardMethod.encodeSuccessEnvelope(sensorData));

script/nnbd_plugins.sh

@@ -14,6 +14,7 @@ readonly NNBD_PLUGINS_LIST=(
   "local_auth"
   "path_provider"
   "plugin_platform_interface"
+  "sensors"
   "share"
   "url_launcher"
   "video_player"