code: def test_page_sort_key_error(self):
      with pytest.raises(AssertionError) as e:
          source_util.page_sort_key(Path("/foo/bar/baz.rs"))
  
      assert str(e.value) == "/foo/bar/baz.rs is not a Python file"
  
file_path: streamlit/lib/tests/streamlit/source_util_test.py
imports: import unittest
  from pathlib import Path
  from unittest.mock import MagicMock, patch
  import pytest
  from parameterized import parameterized
  import streamlit.source_util
  from streamlit.util import calc_md5
label_desc: Use image node_id 2 for calling the PageHelperFunctionTests obj's underlying member method code with example usage: obj.test_page_sort_key_error() without return types