Function allow_move_dir

cpp/src/arrow/filesystem/test_util.h:178–178

- Whether the filesystem allows moving a directory

  virtual bool allow_move_file() const { return true; }
  // - Whether the filesystem allows moving a directory
  virtual bool allow_move_dir() const { return true; }
  // - Whether the filesystem allows moving a directory "over" a non-empty destination
  virtual bool allow_move_dir_over_non_empty_dir() const { return false; }
  // - Whether the filesystem allows appending to a file