anchor.diff:  
     @override
     FlutterVmService get vmService => FakeFlutterVmService();
  -}
  -class MockDevice extends Mock implements Device {
  -  MockDevice() {
  -    when(isSupported()).thenReturn(true);
  +
  +  int runColdCode = 0;
  +
  +  @override
  +  Future<int> runCold({ColdRunner coldRunner, String route}) async {
  +    return runColdCode;
  +  }
  +
  +  @override
  +  Future<void> initLogReader() async { }
  +}
  +
  +class FakeDevice extends Fake implements Device {
  +  @override
  +  bool isSupported() => true;
  +
  +  @override
  +  bool supportsHotReload;
  +
  +  @override
  +  bool supportsHotRestart;
  +
  +  @override
  +  Future<String> get sdkNameAndVersion async => 'Android 10';
  +
  +  @override
  +  String get name => 'test';
  +
  +  @override
  +  Future<TargetPlatform> get targetPlatform async => TargetPlatform.tester;
  +
  +  bool wasDisposed = false;
  +
  +  @override
  +  Future<void> dispose() async {
  +    wasDisposed = true;
     }
   }
   
  
positive.code:     testUsingContext('with traceStartup, env variable', () async {
        fakePlatform.environment[kFlutterTestOutputsDirEnvName] = 'test_output_dir';
  
        final MockDevice mockDevice = MockDevice();
        final MockFlutterDevice mockFlutterDevice = MockFlutterDevice();
        when(mockFlutterDevice.device).thenReturn(mockDevice);
        when(mockFlutterDevice.runCold(
            coldRunner: anyNamed('coldRunner'),
            route: anyNamed('route')
        )).thenAnswer((Invocation invocation) => Future<int>.value(0));
        final List<FlutterDevice> devices = <FlutterDevice>[mockFlutterDevice];
        final File applicationBinary = MemoryFileSystem.test().file('binary');
        final int result = await ColdRunner(
          devices,
  
negative.code:       );
  
        expect(result, 1);
      });
  
      testUsingContext('with traceStartup, no env variable', () async {
        final FakeDevice device = FakeDevice();
        final FakeFlutterDevice flutterDevice = FakeFlutterDevice(device);
        final List<FlutterDevice> devices = <FlutterDevice>[flutterDevice];
        final File applicationBinary = MemoryFileSystem.test().file('binary');
        final int result = await ColdRunner(
          devices,
  