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:     fileSystem.file('app.debug').writeAsBytesSync(<int>[1, 2, 3]);
      fileSystem.file('foo.stack').writeAsStringSync('hello');
  
      await createTestCommandRunner(command)
        .run(const <String>['symbolize', '--debug-info=app.debug', '--input=foo.stack', '--output=results/foo.result']);
  
      expect(fileSystem.file('results/foo.result'), exists);
      expect(fileSystem.file('results/foo.result').readAsBytesSync(), <int>[104, 101, 108, 108, 111, 10]); // hello
    });
  
    testUsingContext('symbolize throws when DwarfSymbolizationService throws', () async {
      command = SymbolizeCommand(
        stdio: stdio,
        fileSystem: fileSystem,
        dwarfSymbolizationService: ThrowingDwarfSymbolizationService(),
      );
  
      fileSystem.file('app.debug').writeAsBytesSync(<int>[1, 2, 3]);
      fileSystem.file('foo.stack').writeAsStringSync('hello');
  
      expect(
        createTestCommandRunner(command).run(const <String>[
  