def test_non_existent_input_paths(default_ext):
    """test with input path set to None"""

    with (
        tempfile.TemporaryDirectory() as tmp_dir_1,
        tempfile.TemporaryDirectory() as tmp_dir_2,
    ):
        input_paths = [None for _ in range(100)]

        filename_maker = focu.UniqueFilenameMaker(
            tmp_dir_1, default_ext=default_ext
        )

        assert isinstance(filename_maker, focu.UniqueFilenameMaker)

        expected = [
            filename_maker.get_output_path(input_path)
            for input_path in input_paths
        ]

        with multiprocessing.Pool(
            processes=4,
            initializer=init_process,
            initargs=(
                {
                    "output_dir": tmp_dir_2,
                    "default_ext": default_ext,
                    "ppid": os.getpid(),
                },
            ),
        ) as pool:
            actual = list(
                pool.imap_unordered(process_get_output_path, input_paths)
            )

        assert len(expected) == len(actual)

        if default_ext:
            for output_paths in (expected, actual):
                for output_path in output_paths:
                    _, ext = os.path.splitext(output_path)
                    assert default_ext == ext
test with input path set to None
tests/unittests/utils/test_unique_filename_maker.py