anchor.diff:  import 'package:flutter_tools/src/base/terminal.dart';
   
   import '../src/common.dart';
  +import '../src/context.dart';
   import 'test_utils.dart';
   
   const String _kInitialVersion = 'v1.9.1';
  
positive.code:   outputPreferences: OutputPreferences.test(wrapText: true),
  ));
  final String flutterBin = fileSystem.path.join(getFlutterRoot(), 'bin', platform.isWindows ? 'flutter.bat' : 'flutter');
  final String dartBin = fileSystem.path.join(getFlutterRoot(), 'bin', platform.isWindows ? 'dart.bat' : 'dart');
  
  /// A test for flutter upgrade & downgrade that checks out a parallel flutter repo.
  void main() {
  
negative.code:     }
    });
  
    testUsingContext('Can upgrade and downgrade a Flutter checkout', () async {
      final Directory testDirectory = parentDirectory.childDirectory('flutter');
      testDirectory.createSync(recursive: true);
  
  