anchor.diff:            'enabled': 'true',
           }
         );
  -      expect(updateResponse.json['enabled'], 'true');
  +      expect(updateResponse.json?['enabled'], 'true');
       });
     });
   }
  
positive.code: 
        flutter = FlutterRunTestDriver(tempDir);
        await flutter.run(withDebugger: true);
        final int port = flutter.vmServicePort;
        vmService = await vmServiceConnectUri('ws://localhost:$port/ws');
      });
  
      tearDown(() async {
        await flutter?.stop();
        tryToDelete(tempDir);
      });
  
  
negative.code: // Copyright 2014 The Flutter Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  import 'package:file/file.dart';
  import 'package:flutter_tools/src/base/file_system.dart';
  