anchor.diff:      expect(result['precompiler-trace'], <String, Object>{});
     });
   }
  -
  -class MockUsage extends Mock implements Usage {}
  
positive.code:       fileSystem: fileSystem,
        logger: logger,
        appFilenamePattern: RegExp(r'lib.*app\.so'),
        flutterUsage: MockUsage(),
      );
  
      final Archive archive = Archive()
  
negative.code:       fileSystem: fileSystem,
        logger: logger,
        appFilenamePattern: RegExp(r'lib.*app\.so'),
        flutterUsage: TestUsage(),
      );
  
      final Directory outputDirectory = fileSystem.directory('example/out/foo.app')
  