anchor.diff:  import 'dart:typed_data';
   
   import 'package:file/memory.dart';
  +import 'package:file_testing/file_testing.dart';
   import 'package:flutter_tools/src/base/common.dart';
   import 'package:flutter_tools/src/base/file_system.dart';
   import 'package:flutter_tools/src/cache.dart';
   import 'package:flutter_tools/src/commands/symbolize.dart';
   import 'package:flutter_tools/src/convert.dart';
  -import 'package:mockito/mockito.dart';
  +import 'package:meta/meta.dart';
  +import 'package:test/fake.dart';
   
   import '../../src/common.dart';
   import '../../src/context.dart';
  
positive.code:   MemoryFileSystem fileSystem;
    FakeStdio stdio;
    SymbolizeCommand command;
    MockDwarfSymbolizationService mockDwarfSymbolizationService;
  
    setUpAll(() {
      Cache.disableLocking();
  
negative.code:   });
  }
  
  class ThrowingDwarfSymbolizationService extends Fake implements DwarfSymbolizationService {
    @override
    Future<void> decode({
      @required Stream<List<int>> input,
      @required IOSink output,
      @required Uint8List symbols,
    }) async {
      throwToolExit('test');
    }
  }
  