def METHOD_NAME(cls) -> None:
    """Load test cases from .toml files and create a 2D map."""
    if cls.test_map is None:
        cls.test_map = {}
        cls.test_files = {
            file.name: tomlkit.loads(file.read_text())
            for file in md_tests_data_root.iterdir()
            if file.suffix == '.toml'
        }
        for md_testname, test_data in cls.test_files.items():
            config = test_data['config']
            exp = test_data.get('expected_output', {})
            # Combine pre-defined profiles with custom profiles
            # and store each test case in test_map[md_testname][md_configname]
            cls.test_map[md_testname] = {  # pylint: disable=E1137
                md_configname: MarkdownCase(
                    md_testname=md_testname,
                    mdtext=test_data['markdown'],  # type: ignore[arg-type]
                    md_configname=md_configname,
                    config=config,
                    expected_output=None
                    if exp.get(md_configname, None) is None
                    else Markup(exp.get(md_configname, None)),
                )
                for md_configname, config in {
                    **{
                        p: None
                        for p in config.get(  # type: ignore[union-attr]
                            'profiles', []
                        )
                    },
                    **config.get(  # type: ignore[union-attr]
                        'custom_profiles', {}
                    ),
                }.items()
            }