add test which covers stdin filename ipynb (#2454)

            # __BLACK_STDIN_FILENAME__ should have been stripped

            report.done.assert_called_with(expected, black.Changed.YES)

    def test_reformat_one_with_stdin_filename_ipynb(self) -> None:

        with patch(

            "black.format_stdin_to_stdout",

            return_value=lambda *args, **kwargs: black.Changed.YES,

        ) as fsts:

            report = MagicMock()

            p = "foo.ipynb"

            path = Path(f"__BLACK_STDIN_FILENAME__{p}")

            expected = Path(p)

            black.reformat_one(

                path,

                fast=True,

                write_back=black.WriteBack.YES,

                mode=DEFAULT_MODE,

                report=report,

            )

            fsts.assert_called_once_with(

                fast=True,

                write_back=black.WriteBack.YES,

                mode=replace(DEFAULT_MODE, is_ipynb=True),

            )

            # __BLACK_STDIN_FILENAME__ should have been stripped

            report.done.assert_called_with(expected, black.Changed.YES)

    def test_reformat_one_with_stdin_and_existing_path(self) -> None:

        with patch(

            "black.format_stdin_to_stdout",