anchor.diff:      fileSystem.file('app.debug').writeAsBytesSync(<int>[1, 2, 3]);
       fileSystem.file('foo.stack').writeAsStringSync('hello');
   
  -    when(mockDwarfSymbolizationService.decode(
  -      input: anyNamed('input'),
  -      output: anyNamed('output'),
  -      symbols: anyNamed('symbols'))
  -    ).thenAnswer((Invocation invocation) async {
  -      // Data is passed correctly to service
  -      expect((await (invocation.namedArguments[#input] as Stream<List<int>>).toList()).first,
  -        utf8.encode('hello'));
  -      expect(invocation.namedArguments[#symbols] as Uint8List, <int>[1, 2, 3,]);
  -      return;
  -    });
  -
       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');
  -
  -    when(mockDwarfSymbolizationService.decode(
  -      input: anyNamed('input'),
  -      output: anyNamed('output'),
  -      symbols: anyNamed('symbols'))
  -    ).thenThrow(ToolExit('test'));
   
       expect(
         createTestCommandRunner(command).run(const <String>[
  
positive.code:   setUp(() {
      fileSystem = MemoryFileSystem.test();
      stdio = FakeStdio();
      mockDwarfSymbolizationService = MockDwarfSymbolizationService();
      command = SymbolizeCommand(
        stdio: stdio,
        fileSystem: fileSystem,
        dwarfSymbolizationService: mockDwarfSymbolizationService,
      );
    });
  
  
negative.code: 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:meta/meta.dart';
  import 'package:test/fake.dart';
  
  import '../../src/common.dart';
  import '../../src/context.dart';
  