code: def test_no_exist_file_is_cached(self):
      revisions = [None, "file-2"]
      expected_references = ["main", "file-2"]
      for revision, expected_reference in zip(
          revisions, expected_references
      ):
          with self.subTest(
              revision
          ), SoftTemporaryDirectory() as cache:
              filename = "this_does_not_exist.txt"
              with self.assertRaises(EntryNotFoundError):
                  # The file does not exist, so we get an exception.
                  hf_hub_download(
                      MODEL_IDENTIFIER,
                      filename,
                      cache_dir=cache,
                      revision=revision,
                  )
  
              expected_directory_name = (
                  f'models--{MODEL_IDENTIFIER.replace("/", "--")}'
              )
              expected_path = os.path.join(
                  cache, expected_directory_name
              )
  
              refs = os.listdir(os.path.join(expected_path, "refs"))
              no_exist_snapshots = os.listdir(
                  os.path.join(expected_path, ".no_exist")
              )
  
              # Only reference should be `main`.
              self.assertListEqual(refs, [expected_reference])
  
              with open(
                  os.path.join(
                      expected_path, "refs", expected_reference
                  )
              ) as f:
                  snapshot_name = f.readline().strip()
  
              # The `main` reference should point to the only snapshot we have downloaded
              self.assertListEqual(no_exist_snapshots, [snapshot_name])
  
              no_exist_path = os.path.join(
                  expected_path, ".no_exist", snapshot_name
              )
              no_exist_content = os.listdir(no_exist_path)
  
              # Only a single file in the no_exist snapshot
              self.assertEqual(len(no_exist_content), 1)
  
              # The no_exist content should be our file
              self.assertEqual(no_exist_content[0], filename)
  
              with open(os.path.join(no_exist_path, filename)) as f:
                  content = f.read().strip()
  
              # The contents of the file should be empty.
              self.assertEqual(content, "")
  
imports: import os
  import time
  import unittest
  from io import BytesIO
  from huggingface_hub import HfApi, hf_hub_download, snapshot_download
  from huggingface_hub.utils import SoftTemporaryDirectory, logging
  from huggingface_hub.utils._errors import EntryNotFoundError
  from .testing_constants import ENDPOINT_STAGING, TOKEN
  from .testing_utils import repo_name, with_production_testing, xfail_on_windows
label_desc: Use image node_id 2 for calling the CacheFileLayoutHfHubDownload obj's underlying member method code with example usage: obj.test_no_exist_file_is_cached() without return types