def METHOD_NAME(tmpdir) -> None:
    valid_extensions = _make_valid_extensions()
    valid_extensions = list(valid_extensions)
    fake_extensions = _make_fake_extensions(seed=42)
    mock_extensions = valid_extensions + fake_extensions
    mock_files = _make_fake_files(mock_extensions, seed=42)
    mockdir = _make_mock_dir(tmpdir, mock_files)
    message = "Found invalid file extensions"
    with pytest.warns(UserWarning, match=message):
        filtered = filter_valid_files(mockdir, valid_extensions=valid_extensions)
    assert all(i not in fake_extensions for i in filtered)