code: def test_key_order_after_copy(self):
      data_files = DataFilesDict(
          {"train": "train.csv", "test": "test.csv"}
      )
      copied_data_files = copy.deepcopy(data_files)
      assert list(copied_data_files.keys()) == list(data_files.keys())
  
imports: import copy
  import os
  from pathlib import Path
  from typing import List
  from unittest.mock import patch
  import fsspec
  import pytest
  from fsspec.registry import _registry
  from fsspec.spec import AbstractFileSystem
  from datasets.data_files import DataFilesDict, DataFilesList, DataFilesPatternsDict, DataFilesPatternsList, _get_data_files_patterns, _get_metadata_files_patterns, _is_inside_unrequested_special_dir, _is_unrequested_hidden_file_or_is_inside_unrequested_hidden_dir, get_data_patterns, resolve_pattern
  from datasets.fingerprint import Hasher
label_desc: Use image node_id 1 for calling the TestDataFilesDict obj's underlying member method code with example usage: obj.test_key_order_after_copy() without return types