anchor.diff:  }
   
   class FileStatMock implements FileStat {
  -  final DateTime changed;
  -  final DateTime modified;
  -  final DateTime accessed;
  -  final FileSystemEntityType type;
  -  final int mode;
  -  final int size;
  +  final DateTime changed = null;
  +  final DateTime modified = null;
  +  final DateTime accessed = null;
  +  final FileSystemEntityType type = null;
  +  final int mode = null;
  +  final int size = null;
   
     FileStatMock();
   
  
positive.code:   void createSync({bool recursive: false}) {}
    Future<Directory> createTemp([String prefix]) => null;
    Directory createTempSync([String prefix]) => null;
    Future<String> resolveSymbolicLinks() => null;
    String resolveSymbolicLinksSync() => null;
    Future<Directory> rename(String newPath) => null;
  
negative.code:   void createSync(String target, {bool recursive: false}) {}
    void updateSync(String target) {}
    Future<Link> update(String target) => null;
    Future<bool> exists() => null;
    bool existsSync() => false;
    Future<String> resolveSymbolicLinks() => null;
    String resolveSymbolicLinksSync() => null;
    Future<Link> rename(String newPath) => null;
  