apply partially the upcoming unnecessary_lambdas (#8810)

dev/devicelab/lib/framework/utils.dart

@@ -430,9 +430,7 @@ Future<Null> runAndCaptureAsyncStacks(Future<Null> callback()) {
   Chain.capture(() async {
     await callback();
     completer.complete();
-  }, onError: (dynamic error, Chain chain) async {
-    completer.completeError(error, chain);
-  });
+  }, onError: completer.completeError);
   return completer.future;
 }
 

examples/flutter_gallery/lib/demo/animation/home.dart

@@ -386,7 +386,7 @@ class _AnimationDemoHomeState extends State<AnimationDemoHome> {
       backgroundColor: _kAppBackgroundColor,
       body: new Builder(
         // Insert an element so that _buildBody can find the PrimaryScrollController.
-        builder: (BuildContext context) => _buildBody(context),
+        builder: _buildBody,
       ),
     );
   }

examples/flutter_gallery/lib/demo/shrine/shrine_page.dart

@@ -108,9 +108,7 @@ class ShrinePageState extends State<ShrinePage> {
           new IconButton(
             icon: new Icon(Icons.shopping_cart),
             tooltip: 'Shopping cart',
-            onPressed: () {
-              _showShoppingCart();
-            }
+            onPressed: _showShoppingCart
           ),
           new PopupMenuButton<ShrineAction>(
             itemBuilder: (BuildContext context) => <PopupMenuItem<ShrineAction>>[

examples/layers/services/isolate.dart

@@ -183,9 +183,7 @@ class CalculationManager {
       onProgressListener: (double completed, double total) {
         sender.send(<double>[ completed, total ]);
       },
-      onResultListener: (String result) {
-        sender.send(result);
-      },
+      onResultListener: sender.send,
       data: message.data
     );
     calculator.run();

examples/stocks/lib/stock_home.dart

@@ -24,7 +24,7 @@ class _NotImplementedDialog extends StatelessWidget {
       content: new Text('This feature has not yet been implemented.'),
       actions: <Widget>[
         new FlatButton(
-          onPressed: () { debugDumpApp(); },
+          onPressed: debugDumpApp,
           child: new Row(
             children: <Widget>[
               new Icon(

examples/stocks/lib/stock_settings.dart

@@ -105,7 +105,7 @@ class StockSettingsState extends State<StockSettings> {
     final List<Widget> rows = <Widget>[
       new DrawerItem(
         icon: new Icon(Icons.thumb_up),
-        onPressed: () => _confirmOptimismChange(),
+        onPressed: _confirmOptimismChange,
         child: new Row(
           children: <Widget>[
             new Expanded(child: new Text('Everything is awesome')),

packages/flutter/lib/src/gestures/multitap.dart

@@ -207,7 +207,7 @@ class DoubleTapGestureRecognizer extends GestureRecognizer {
   }
 
   void _startDoubleTapTimer() {
-    _doubleTapTimer ??= new Timer(kDoubleTapTimeout, () => _reset());
+    _doubleTapTimer ??= new Timer(kDoubleTapTimeout, _reset);
   }
 
   void _stopDoubleTapTimer() {

packages/flutter/lib/src/material/bottom_navigation_bar.dart

@@ -221,9 +221,7 @@ class _BottomNavigationBarState extends State<BottomNavigationBar> with TickerPr
   // animations such that their resulting flex values will add up to the desired
   // value.
   void _computeWeight() {
-    final Iterable<Animation<double>> animating = _animations.where(
-      (Animation<double> animation) => _isAnimating(animation)
-    );
+    final Iterable<Animation<double>> animating = _animations.where(_isAnimating);
 
     if (animating.isNotEmpty) {
       final double sum = animating.fold(0.0, (double sum, Animation<double> animation) {
@@ -246,11 +244,8 @@ class _BottomNavigationBarState extends State<BottomNavigationBar> with TickerPr
 
   double _xOffset(int index) {
     double weightSum(Iterable<Animation<double>> animations) {
-      return animations.map(
-        // We're adding flex values instead of animation values to have correct
-        // ratios.
-        (Animation<double> animation) => _flex(animation)
-      ).fold(0.0, (double sum, double value) => sum + value);
+      // We're adding flex values instead of animation values to have correct ratios.
+      return animations.map(_flex).fold(0.0, (double sum, double value) => sum + value);
     }
 
     final double allWeights = weightSum(_animations);

packages/flutter/lib/src/material/input.dart

@@ -127,9 +127,7 @@ class _InputFieldState extends State<InputField> {
       new GestureDetector(
         key: focusKey == _focusKey ? _focusKey : null,
         behavior: HitTestBehavior.opaque,
-        onTap: () {
-          requestKeyboard();
-        },
+        onTap: requestKeyboard,
         // Since the focusKey may have been created here, defer building the
         // EditableText until the focusKey's context has been set. This is
         // necessary because the EditableText will check the focus, like

packages/flutter/lib/src/material/scaffold.dart

@@ -679,7 +679,7 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin {
       _currentBottomSheet = new PersistentBottomSheetController<T>._(
         bottomSheet,
         completer,
-        () => entry.remove(),
+        entry.remove,
         (VoidCallback fn) { bottomSheetKey.currentState?.setState(fn); }
       );
     });

packages/flutter/lib/src/services/image_decoder.dart

@@ -13,8 +13,6 @@ import 'dart:ui' as ui show Image, decodeImageFromList;
 /// resolves to [null].
 Future<ui.Image> decodeImageFromList(Uint8List list) {
   final Completer<ui.Image> completer = new Completer<ui.Image>();
-  ui.decodeImageFromList(list, (ui.Image image) {
-    completer.complete(image);
-  });
+  ui.decodeImageFromList(list, completer.complete);
   return completer.future;
 }

packages/flutter/test/animation/animation_controller_test.dart

@@ -52,9 +52,7 @@ void main() {
     final List<double> valueLog = <double>[];
     final List<AnimationStatus> log = <AnimationStatus>[];
     controller
-      ..addStatusListener((AnimationStatus status) {
-        log.add(status);
-      })
+      ..addStatusListener(log.add)
       ..addListener(() {
         valueLog.add(controller.value);
       });
@@ -115,9 +113,7 @@ void main() {
     final List<double> valueLog = <double>[];
     final List<AnimationStatus> statusLog = <AnimationStatus>[];
     controller
-      ..addStatusListener((AnimationStatus status) {
-        statusLog.add(status);
-      })
+      ..addStatusListener(statusLog.add)
       ..addListener(() {
         valueLog.add(controller.value);
       });
@@ -143,9 +139,7 @@ void main() {
     final List<double> valueLog = <double>[];
     final List<AnimationStatus> statusLog = <AnimationStatus>[];
     controller
-      ..addStatusListener((AnimationStatus status) {
-        statusLog.add(status);
-      })
+      ..addStatusListener(statusLog.add)
       ..addListener(() {
         valueLog.add(controller.value);
       });

packages/flutter/test/foundation/service_extensions_test.dart

@@ -58,9 +58,7 @@ class TestServiceExtensionsBinding extends BindingBase
 
   Future<Null> flushMicrotasks() {
     final Completer<Null> completer = new Completer<Null>();
-    new Timer(const Duration(), () {
-      completer.complete();
-    });
+    new Timer(const Duration(), completer.complete);
     return completer.future;
   }
 }

packages/flutter/test/gestures/gesture_binding_test.dart

@@ -41,7 +41,7 @@ void main() {
     );
 
     final List<PointerEvent> events = <PointerEvent>[];
-    _binding.callback = (PointerEvent event) => events.add(event);
+    _binding.callback = events.add;
 
     ui.window.onPointerDataPacket(packet);
     expect(events.length, 2);
@@ -59,7 +59,7 @@ void main() {
     );
 
     final List<PointerEvent> events = <PointerEvent>[];
-    _binding.callback = (PointerEvent event) => events.add(event);
+    _binding.callback = events.add;
 
     ui.window.onPointerDataPacket(packet);
     expect(events.length, 3);
@@ -85,7 +85,7 @@ void main() {
     );
 
     final List<PointerEvent> events = <PointerEvent>[];
-    _binding.callback = (PointerEvent event) => events.add(event);
+    _binding.callback = events.add;
 
     ui.window.onPointerDataPacket(packet);
     expect(events.length, 3);
@@ -104,7 +104,7 @@ void main() {
     );
 
     final List<PointerEvent> events = <PointerEvent>[];
-    _binding.callback = (PointerEvent event) => events.add(event);
+    _binding.callback = events.add;
 
     ui.window.onPointerDataPacket(packet);
     expect(events.length, 2);

packages/flutter/test/material/radio_test.dart

@@ -16,9 +16,7 @@ void main() {
           key: key,
           value: 1,
           groupValue: 2,
-          onChanged: (int value) {
-            log.add(value);
-          },
+          onChanged: log.add,
         ),
       ),
     ));
@@ -34,9 +32,7 @@ void main() {
           key: key,
           value: 1,
           groupValue: 1,
-          onChanged: (int value) {
-            log.add(value);
-          },
+          onChanged: log.add,
           activeColor: Colors.green[500],
         ),
       ),

packages/flutter/test/widgets/draggable_test.dart

@@ -25,9 +25,7 @@ void main() {
             builder: (BuildContext context, List<int> data, List<dynamic> rejects) {
               return new Container(height: 100.0, child: new Text('Target'));
             },
-            onAccept: (int data) {
-              accepted.add(data);
-            }
+            onAccept: accepted.add
           ),
         ]
       )
@@ -539,9 +537,7 @@ void main() {
             builder: (BuildContext context, List<int> data, List<dynamic> rejects) {
               return new Container(height: 100.0, child: new Text('Target'));
             },
-            onAccept: (int data) {
-              accepted.add(data);
-            }
+            onAccept: accepted.add
           ),
         ]
       )
@@ -731,9 +727,7 @@ void main() {
                     )
                   );
                 },
-                onAccept: (int data) {
-                  acceptedInts.add(data);
-                }
+                onAccept: acceptedInts.add
               ),
               new DragTarget<double>(
                 builder: (BuildContext context, List<double> data, List<dynamic> rejects) {
@@ -744,9 +738,7 @@ void main() {
                     )
                   );
                 },
-                onAccept: (double data) {
-                  acceptedDoubles.add(data);
-                }
+                onAccept: acceptedDoubles.add
               ),
             ]
           )
@@ -842,9 +834,7 @@ void main() {
                       child: new Text('Target1')
                     )
                   );
-                }, onAccept: (DragTargetData data) {
-                  acceptedDragTargetDatas.add(data);
-                }
+                }, onAccept: acceptedDragTargetDatas.add
               ),
               new DragTarget<ExtendedDragTargetData>(
                 builder: (BuildContext context, List<ExtendedDragTargetData> data, List<dynamic> rejects) {
@@ -855,9 +845,7 @@ void main() {
                     )
                   );
                 },
-                onAccept: (ExtendedDragTargetData data) {
-                  acceptedExtendedDragTargetDatas.add(data);
-                }
+                onAccept: acceptedExtendedDragTargetDatas.add
               ),
             ]
           )
@@ -901,9 +889,7 @@ void main() {
               builder: (BuildContext context, List<int> data, List<dynamic> rejects) {
                 return new Container(height: 100.0, child: new Text('Target'));
               },
-              onAccept: (int data) {
-                accepted.add(data);
-              }
+              onAccept: accepted.add
             ),
           ]
         )
@@ -1140,9 +1126,7 @@ void main() {
                   builder: (BuildContext context, List<int> data, List<dynamic> rejects) {
                     return new Container(height: 100.0, child: new Text('Target'));
                   },
-                  onAccept: (int data) {
-                    accepted.add(data);
-                  }
+                  onAccept: accepted.add
               ),
             ]
         )
@@ -1169,9 +1153,7 @@ void main() {
                   builder: (BuildContext context, List<int> data, List<dynamic> rejects) {
                     return new Container(height: 100.0, child: new Text('Target'));
                   },
-                  onAccept: (int data) {
-                    accepted.add(data);
-                  }
+                  onAccept: accepted.add
               ),
             ]
         )
@@ -1258,9 +1240,7 @@ Future<Null> _testChildAnchorFeedbackPosition({WidgetTester tester, double top:
               builder: (BuildContext context, List<int> data, List<dynamic> rejects) {
                 return new Container(height: 100.0, child: new Text('Target'));
               },
-              onAccept: (int data) {
-                accepted.add(data);
-              }
+              onAccept: accepted.add
             ),
           ]
         )

packages/flutter/test/widgets/page_view_test.dart

@@ -223,9 +223,7 @@ void main() {
   testWidgets('Page changes at halfway point', (WidgetTester tester) async {
     final List<int> log = <int>[];
     await tester.pumpWidget(new PageView(
-      onPageChanged: (int page) {
-        log.add(page);
-      },
+      onPageChanged: log.add,
       children: kStates.map<Widget>((String state) => new Text(state)).toList(),
     ));
 

packages/flutter/test/widgets/raw_keyboard_listener_test.dart

@@ -28,9 +28,7 @@ void main() {
 
     await tester.pumpWidget(new RawKeyboardListener(
       focused: true,
-      onKey: (RawKeyEvent event) {
-        events.add(event);
-      },
+      onKey: events.add,
       child: new Container(),
     ));
 
@@ -59,9 +57,7 @@ void main() {
 
     await tester.pumpWidget(new RawKeyboardListener(
       focused: true,
-      onKey: (RawKeyEvent event) {
-        events.add(event);
-      },
+      onKey: events.add,
       child: new Container(),
     ));
 

packages/flutter_driver/lib/src/timeline_summary.dart

@@ -160,7 +160,7 @@ class TimelineSummary {
 
     return durations
         .map<double>((Duration duration) => duration.inMilliseconds.toDouble())
-        .reduce((double a, double b) => math.max(a, b));
+        .reduce(math.max);
   }
 
   List<TimedEvent> _extractGpuRasterizerDrawEvents() => _extractBeginEndEvents('GPURasterizer::Draw');

packages/flutter_test/lib/src/binding.dart

@@ -889,7 +889,7 @@ class _LiveTestRenderView extends RenderView {
         .keys
         .where((int pointer) => _pointers[pointer].decay == 0)
         .toList()
-        .forEach((int pointer) { _pointers.remove(pointer); });
+        .forEach(_pointers.remove);
       if (dirty)
         scheduleMicrotask(markNeedsPaint);
     }

packages/flutter_tools/lib/src/base/io.dart

@@ -74,7 +74,7 @@ export 'dart:io'
 /// Exits the process with the given [exitCode].
 typedef void ExitFunction(int exitCode);
 
-final ExitFunction _defaultExitFunction = (int exitCode) => io.exit(exitCode);
+final ExitFunction _defaultExitFunction = io.exit;
 
 ExitFunction _exitFunction = _defaultExitFunction;
 

packages/flutter_tools/lib/src/cache.dart

@@ -231,9 +231,7 @@ class MaterialFonts {
     ).then<Null>((Null value) {
       cache.setStampFor(kName, cache.getVersionFor(kName));
       status.stop();
-    }).whenComplete(() {
-      status.cancel();
-    });
+    }).whenComplete(status.cancel);
   }
 }
 
@@ -376,8 +374,6 @@ class FlutterEngine {
     final Status status = logger.startProgress(message, expectSlowOperation: true);
     return Cache._downloadFileToCache(Uri.parse(url), dest, true).then<Null>((Null value) {
       status.stop();
-    }).whenComplete(() {
-      status.cancel();
-    });
+    }).whenComplete(status.cancel);
   }
 }

packages/flutter_tools/lib/src/commands/analyze_continuously.dart

@@ -169,7 +169,7 @@ class AnalysisServer {
     _process.exitCode.whenComplete(() => _process = null);
 
     final Stream<String> errorStream = _process.stderr.transform(UTF8.decoder).transform(const LineSplitter());
-    errorStream.listen((String error) => printError(error));
+    errorStream.listen(printError);
 
     final Stream<String> inStream = _process.stdout.transform(UTF8.decoder).transform(const LineSplitter());
     inStream.listen(_handleServerResponse);

packages/flutter_tools/lib/src/commands/daemon.dart

@@ -88,7 +88,7 @@ class Daemon {
 
     // Start listening.
     commandStream.listen(
-      (Map<String, dynamic> request) => _handleRequest(request),
+      _handleRequest,
       onDone: () {
         if (!_onExitCompleter.isCompleted)
             _onExitCompleter.complete(0);
@@ -264,7 +264,7 @@ class DaemonDomain extends Domain {
   }
 
   Future<Null> shutdown(Map<String, dynamic> args) {
-    Timer.run(() => daemon.shutdown());
+    Timer.run(daemon.shutdown);
     return new Future<Null>.value();
   }
 

packages/flutter_tools/lib/src/device.dart

@@ -277,7 +277,7 @@ abstract class Device {
   }
 
   static void printDevices(List<Device> devices) {
-    descriptions(devices).forEach((String msg) => printStatus(msg));
+    descriptions(devices).forEach(printStatus);
   }
 }
 

packages/flutter_tools/lib/src/ios/simulators.dart

@@ -609,9 +609,7 @@ class _IOSSimulatorLogReader extends DeviceLogReader {
 
   _IOSSimulatorLogReader(this.device, ApplicationPackage app) {
     _linesController = new StreamController<String>.broadcast(
-      onListen: () {
-        _start();
-      },
+      onListen: _start,
       onCancel: _stop
     );
     _appName = app == null ? null : app.name.replaceAll('.app', '');

packages/flutter_tools/lib/src/resident_runner.dart

@@ -230,9 +230,7 @@ abstract class ResidentRunner {
       throwToolExit('No Flutter view is available');
 
     // Listen for service protocol connection to close.
-    vmService.done.whenComplete(() {
-      appFinished();
-    });
+    vmService.done.whenComplete(appFinished);
   }
 
   /// Returns [true] if the input has been handled by this function.
@@ -321,9 +319,7 @@ abstract class ResidentRunner {
         printHelp(details: false);
       }
       terminal.singleCharMode = true;
-      terminal.onCharInput.listen((String code) {
-        processTerminalInput(code);
-      });
+      terminal.onCharInput.listen(processTerminalInput);
     }
   }
 

packages/flutter_tools/lib/src/runner/flutter_command_runner.dart

@@ -250,7 +250,7 @@ class FlutterCommandRunner extends CommandRunner<Null> {
     }
 
     // The Android SDK could already have been set by tests.
-    context.putIfAbsent(AndroidSdk, () => AndroidSdk.locateAndroidSdk());
+    context.putIfAbsent(AndroidSdk, AndroidSdk.locateAndroidSdk);
 
     if (globalResults['version']) {
       flutterUsage.sendCommand('version');

packages/flutter_tools/lib/src/test/flutter_platform.dart

@@ -222,7 +222,7 @@ class _FlutterPlatform extends PlatformPlugin {
           processObservatoryPort = detectedPort;
         },
         startTimeoutTimer: () {
-          new Future<_InitialResult>.delayed(_kTestStartupTimeout, () => timeout.complete());
+          new Future<_InitialResult>.delayed(_kTestStartupTimeout, timeout.complete);
         },
       );
 
@@ -265,7 +265,7 @@ class _FlutterPlatform extends PlatformPlugin {
           final Completer<Null> harnessDone = new Completer<Null>();
           final StreamSubscription<dynamic> harnessToTest = controller.stream.listen(
             (dynamic event) { testSocket.add(JSON.encode(event)); },
-            onDone: () { harnessDone.complete(); },
+            onDone: harnessDone.complete,
             onError: (dynamic error, dynamic stack) {
               // If you reach here, it's unlikely we're going to be able to really handle this well.
               printError('test harness controller stream experienced an unexpected error\ntest: $testPath\nerror: $error');
@@ -285,7 +285,7 @@ class _FlutterPlatform extends PlatformPlugin {
               assert(encodedEvent is String); // we shouldn't ever get binary messages
               controller.sink.add(JSON.decode(encodedEvent));
             },
-            onDone: () { testDone.complete(); },
+            onDone: testDone.complete,
             onError: (dynamic error, dynamic stack) {
               // If you reach here, it's unlikely we're going to be able to really handle this well.
               printError('test socket stream experienced an unexpected error\ntest: $testPath\nerror: $error');
@@ -559,9 +559,7 @@ class _FlutterPlatformStreamSinkWrapper<S> implements StreamSink<S> {
       (List<dynamic> value) {
         _done.complete();
       },
-      onError: (dynamic error, StackTrace stack) {
-        _done.completeError(error, stack);
-      },
+      onError: _done.completeError,
     );
     return done;
   }

packages/flutter_tools/lib/src/vmservice.dart

@@ -37,9 +37,7 @@ const Duration kLongRequestTimeout = const Duration(minutes: 1);
 class VMService {
   VMService._(this._peer, this.httpAddress, this.wsAddress, this._requestTimeout) {
     _vm = new VM._empty(this);
-    _peer.listen().catchError((dynamic e, StackTrace stackTrace) {
-      _connectionError.completeError(e, stackTrace);
-    });
+    _peer.listen().catchError(_connectionError.completeError);
 
     _peer.registerMethod('streamNotify', (rpc.Parameters event) {
       _handleStreamNotify(event.asMap);
@@ -549,7 +547,7 @@ class VM extends ServiceObjectOwner {
         toRemove.add(id);
       }
     });
-    toRemove.forEach((String id) => _isolateCache.remove(id));
+    toRemove.forEach(_isolateCache.remove);
     _buildIsolateList();
   }
 

packages/flutter_tools/lib/src/vmservice_record_replay.dart

@@ -157,13 +157,8 @@ class _RecordingStream {
         _recording.add(new _Response.fromString(element));
         _controller.add(element);
       },
-      onError: (dynamic error, StackTrace stackTrace) {
-        // We currently don't support recording of errors.
-        _controller.addError(error, stackTrace);
-      },
-      onDone: () {
-        _controller.close();
-      },
+      onError: _controller.addError, // We currently don't support recording of errors.
+      onDone: _controller.close,
     );
   }
 

packages/flutter_tools/test/daemon_test.dart

@@ -51,7 +51,7 @@ void main() {
       final StreamController<Map<String, dynamic>> responses = new StreamController<Map<String, dynamic>>();
       daemon = new Daemon(
         commands.stream,
-        (Map<String, dynamic> result) => responses.add(result),
+        responses.add,
         notifyingLogger: notifyingLogger
       );
       commands.add(<String, dynamic>{'id': 0, 'method': 'daemon.version'});
@@ -69,7 +69,7 @@ void main() {
         final StreamController<Map<String, dynamic>> responses = new StreamController<Map<String, dynamic>>();
         daemon = new Daemon(
           commands.stream,
-          (Map<String, dynamic> result) => responses.add(result),
+          responses.add,
           notifyingLogger: notifyingLogger
         );
         printError('daemon.logMessage test');
@@ -95,7 +95,7 @@ void main() {
           final StreamController<Map<String, dynamic>> responses = new StreamController<Map<String, dynamic>>();
           daemon = new Daemon(
             commands.stream,
-            (Map<String, dynamic> result) => responses.add(result),
+            responses.add,
             notifyingLogger: notifyingLogger,
             logToStdout: true
           );
@@ -115,7 +115,7 @@ void main() {
       final StreamController<Map<String, dynamic>> responses = new StreamController<Map<String, dynamic>>();
       daemon = new Daemon(
         commands.stream,
-        (Map<String, dynamic> result) => responses.add(result),
+        responses.add,
         notifyingLogger: notifyingLogger
       );
       commands.add(<String, dynamic>{'id': 0, 'method': 'daemon.shutdown'});
@@ -134,7 +134,7 @@ void main() {
       final StreamController<Map<String, dynamic>> responses = new StreamController<Map<String, dynamic>>();
       daemon = new Daemon(
         commands.stream,
-        (Map<String, dynamic> result) => responses.add(result),
+        responses.add,
         daemonCommand: command,
         notifyingLogger: notifyingLogger
       );
@@ -155,7 +155,7 @@ void main() {
       final StreamController<Map<String, dynamic>> responses = new StreamController<Map<String, dynamic>>();
       daemon = new Daemon(
         commands.stream,
-        (Map<String, dynamic> result) => responses.add(result),
+        responses.add,
         daemonCommand: command,
         notifyingLogger: notifyingLogger
       );
@@ -176,7 +176,7 @@ void main() {
       final StreamController<Map<String, dynamic>> responses = new StreamController<Map<String, dynamic>>();
       daemon = new Daemon(
           commands.stream,
-              (Map<String, dynamic> result) => responses.add(result),
+          responses.add,
           daemonCommand: command,
           notifyingLogger: notifyingLogger
       );
@@ -203,7 +203,7 @@ void main() {
       final StreamController<Map<String, dynamic>> responses = new StreamController<Map<String, dynamic>>();
       daemon = new Daemon(
         commands.stream,
-        (Map<String, dynamic> result) => responses.add(result),
+        responses.add,
         daemonCommand: command,
         notifyingLogger: notifyingLogger
       );
@@ -221,7 +221,7 @@ void main() {
       final StreamController<Map<String, dynamic>> responses = new StreamController<Map<String, dynamic>>();
       daemon = new Daemon(
         commands.stream,
-        (Map<String, dynamic> result) => responses.add(result),
+        responses.add,
         notifyingLogger: notifyingLogger
       );
       commands.add(<String, dynamic>{'id': 0, 'method': 'device.getDevices'});

packages/flutter_tools/test/drive_test.dart

@@ -248,7 +248,7 @@ void main() {
         expect(device.name, 'mock-simulator');
       }, overrides: <Type, Generator>{
         FileSystem: () => fs,
-        Platform: () => macOsPlatform(),
+        Platform: macOsPlatform,
       });
 
       testUsingContext('uses existing Android device if and there are no simulators', () async {
@@ -261,7 +261,7 @@ void main() {
         expect(device.name, 'mock-android-device');
       }, overrides: <Type, Generator>{
         FileSystem: () => fs,
-        Platform: () => macOsPlatform(),
+        Platform: macOsPlatform,
       });
 
       testUsingContext('launches emulator', () async {
@@ -275,7 +275,7 @@ void main() {
         expect(device.name, 'new-simulator');
       }, overrides: <Type, Generator>{
         FileSystem: () => fs,
-        Platform: () => macOsPlatform(),
+        Platform: macOsPlatform,
       });
     });
 
@@ -288,7 +288,7 @@ void main() {
         expect(await findTargetDevice(), isNull);
       }, overrides: <Type, Generator>{
         FileSystem: () => fs,
-        Platform: () => platform(),
+        Platform: platform,
       });
 
       testUsingContext('uses existing Android device', () async {
@@ -300,7 +300,7 @@ void main() {
         expect(device.name, 'mock-android-device');
       }, overrides: <Type, Generator>{
         FileSystem: () => fs,
-        Platform: () => platform(),
+        Platform: platform,
       });
     }