anchor.diff:          mockProcessManager = new MockProcessManager();
           mockProcessManager.processFactory =
               (List<String> commands) => mockProcess;
  +
  +        mockArtifacts = new MockArtifacts();
  +        final String artifactPath = fs.path.join(flutterRoot, 'artifact');
  +        fs.file(artifactPath).createSync(recursive: true);
  +        when(mockArtifacts.getArtifactPath(any)).thenReturn(artifactPath);
  +
  +        mockKernelCompiler = new MockKernelCompiler();
         });
   
         testUsingContext('not debug', () async {
           final LaunchResult result = await device.startApp(null,
               mainPath: mainPath,
               debuggingOptions: new DebuggingOptions.disabled(
  -                const BuildInfo(BuildMode.release, null)));
  +                const BuildInfo(BuildMode.release, null, previewDart2: true)));
           expect(result.started, isFalse);
         }, overrides: startOverrides);
   
  
positive.code: 
  import 'package:file/file.dart';
  import 'package:file/memory.dart';
  import 'package:flutter_tools/src/base/platform.dart';
  import 'package:flutter_tools/src/build_info.dart';
  import 'package:flutter_tools/src/cache.dart';
  import 'package:flutter_tools/src/device.dart';
  import 'package:flutter_tools/src/tester/flutter_tester.dart';
  import 'package:process/process.dart';
  
  import '../src/common.dart';
  
negative.code:           await device.startApp(null,
                mainPath: mainPath,
                debuggingOptions: new DebuggingOptions.disabled(
                    const BuildInfo(BuildMode.debug, null, previewDart2: true)));
          }, throwsToolExit());
        }, overrides: startOverrides);
  
  