anchor.diff:        new File(path.join(testPath, 'dir2/file')).createSync();
   
         var files = [];
  -      visitDirectory(testDir, (e) {
  +      return visitDirectory(testDir, (e) {
           files.add(e);
           return new Future.value(!e.path.endsWith('dir2'));
         }).then((_) {
  
positive.code: 
        var results = [];
  
        visitDirectory(testDir, (FileSystemEntity e) {
          if (e is File) {
            results.add("file: ${e.path}");
          } else if (e is Directory) {
  
negative.code:       var dir = new Directory(path.join(testPath, 'dir'))..createSync();
        new Link(path.join(testPath, 'dir/link')).createSync('../dir');
        var files = [];
        return visitDirectory(dir, (e) {
          files.add(e);
          return new Future.value(true);
        }).then((_) {
  