code: def test_cached_files_are_used_when_internet_is_down(self):
      # A mock response for an HTTP head request to emulate server down
      response_mock = mock.Mock()
      response_mock.status_code = 500
      response_mock.headers = {}
      response_mock.raise_for_status.side_effect = HTTPError
      response_mock.json.return_value = {}
  
      # Download this model to make sure it's in the cache.
      _ = BertTokenizer.from_pretrained(
          "hf-internal-testing/tiny-random-bert"
      )
  
      # Under the mock environment we get a 500 error when trying to reach the tokenizer.
      with mock.patch(
          "requests.Session.request", return_value=response_mock
      ) as mock_head:
          _ = BertTokenizer.from_pretrained(
              "hf-internal-testing/tiny-random-bert"
          )
          # This check we did call the fake head request
          mock_head.assert_called()
  
imports: import os
  import sys
  import tempfile
  import unittest
  import unittest.mock
  from pathlib import Path
  from huggingface_hub import HfFolder, delete_repo
  from huggingface_hub.file_download import http_get
  from requests.exceptions import HTTPError
  from transformers import AlbertTokenizer, AutoTokenizer, BertTokenizer, BertTokenizerFast, GPT2TokenizerFast, is_tokenizers_available
  from transformers.testing_utils import TOKEN, USER, is_staging_test, require_tokenizers
  from transformers.tokenization_utils import Trie
  from test_module.custom_tokenization import CustomTokenizer
label_desc: Use image node_id 1 for calling the TokenizerUtilTester obj's underlying member method code with example usage: obj.test_cached_files_are_used_when_internet_is_down() without return types