code: def test_list_nonexistent_directory() -> None:
      root = "./non-existent-directory"
      assert not os.path.exists(root)
      with pytest.raises(FileNotFoundError, match=root):
          storage.StorageManager._list_directory(root)
  
imports: import os
  from typing import Optional
  from unittest import mock
  import pytest
  from determined import core
  from determined.common import storage
label_desc: Use image node_id 7 for calling a global function with example usage: test_list_nonexistent_directory() without return types