anchor.diff:  
       test('compile to JavaScript', () async {
         var file = File('${tempDir.path}/foo.dart')..createSync();
  -      file.writeAsStringSync("main() {}\n");
  -      var packages = File('${tempDir.path}/.packages')
  -        ..createSync()
  -        ..writeAsStringSync("\n");
  +      file.writeAsStringSync("main() {\n}\n");
  +      var package_config =
  +          File('${tempDir.path}/.dart_tool/package_config.json')
  +            ..createSync(recursive: true)
  +            ..writeAsStringSync('''
  +  {
  +    "configVersion": 2,
  +    "packages": [
  +      {
  +        "name": "hello",
  +        "rootUri": "../",
  +        "packageUri": "./"
  +      }
  +    ]
  +  }
  +  ''');
         var dillFile = File('${tempDir.path}/app.dill');
   
         expect(dillFile.existsSync(), false);
  
positive.code:         '--incremental',
          '--platform=${ddcPlatformKernel.path}',
          '--output-dill=${dillFile.path}',
          '--packages=${packages.path}',
          '--target=dartdevc',
          file.path,
        ];
  
  
negative.code: 
      test('compile expression to Javascript', () async {
        var file = File('${tempDir.path}/foo.dart')..createSync();
        file.writeAsStringSync("main() {\n}\n");
        var package_config =
            File('${tempDir.path}/.dart_tool/package_config.json')
              ..createSync(recursive: true)
              ..writeAsStringSync('''
    {
      "configVersion": 2,
      "packages": [
        {
          "name": "hello",
          "rootUri": "../",
          "packageUri": "./"
        }
      ]
    }
    ''');
  
        var library = 'package:hello/foo.dart';
        var module = 'packages/hello/foo.dart';
  