anchor.diff:  import 'package:flutter_tools/src/base/os.dart';
   import 'package:flutter_tools/src/base/platform.dart';
   import 'package:flutter_tools/src/build_info.dart';
  -import 'package:mockito/mockito.dart';
  -import 'package:process/process.dart';
   
   import '../../src/common.dart';
   import '../../src/context.dart';
  
positive.code:     );
    });
  
    testWithoutContext('If unzip throws an ArgumentError, display an install message', () {
      final FileSystem fileSystem = MemoryFileSystem.test();
      when(mockProcessManager.runSync(
        <String>['unzip', '-o', '-q', 'foo.zip', '-d', fileSystem.currentDirectory.path],
      )).thenThrow(ArgumentError());
  
      final OperatingSystemUtils linuxOsUtils = OperatingSystemUtils(
        fileSystem: fileSystem,
        logger: BufferLogger.test(),
        platform: FakePlatform(operatingSystem: 'linux'),
        processManager: mockProcessManager,
      );
  
      expect(
        () => linuxOsUtils.unzip(fileSystem.file('foo.zip'), fileSystem.currentDirectory),
        throwsToolExit(
          message: 'Missing "unzip" tool. Unable to extract foo.zip.\n'
          'Consider running "sudo apt-get install unzip".'),
      );
  
      final OperatingSystemUtils macOSUtils = OperatingSystemUtils(
        fileSystem: fileSystem,
        logger: BufferLogger.test(),
        platform: FakePlatform(operatingSystem: 'macos'),
        processManager: mockProcessManager,
      );
  
      expect(
        () => macOSUtils.unzip(fileSystem.file('foo.zip'), fileSystem.currentDirectory),
        throwsToolExit
        (message: 'Missing "unzip" tool. Unable to extract foo.zip.\n'
          'Consider running "brew install unzip".'),
      );
  
      final OperatingSystemUtils unknownOsUtils = OperatingSystemUtils(
        fileSystem: fileSystem,
        logger: BufferLogger.test(),
        platform: FakePlatform(operatingSystem: 'fuchsia'),
        processManager: mockProcessManager,
      );
  
      expect(
        () => unknownOsUtils.unzip(fileSystem.file('foo.zip'), fileSystem.currentDirectory),
        throwsToolExit
        (message: 'Missing "unzip" tool. Unable to extract foo.zip.\n'
          'Please install unzip.'),
      );
    });
  
    testWithoutContext('stream compression level', () {
      expect(OperatingSystemUtils.gzipLevel1.level, equals(1));
    });
  }
  
  class MockProcessManager extends Mock implements ProcessManager {}
  
negative.code: const String kPath2 = '/another/bin/$kExecutable';
  
  void main() {
    FakeProcessManager fakeProcessManager;
  
    setUp(() {
      fakeProcessManager = FakeProcessManager.list(<FakeCommand>[]);
    });
  
  