# File lib/fakefs/file_system.rb, line 86
    def chdir(dir, &blk)
      new_dir = find(dir)
      dir_levels.push dir if blk

      fail Errno::ENOENT, dir unless new_dir

      dir_levels.push dir unless blk
      yield(dir) if blk
    ensure
      dir_levels.pop if blk
    end