def test_styles_existence(styles_in_scienceplots_per_folder):
    """Check all styles are available in matplotlib."""
    for folder, styles in styles_in_scienceplots_per_folder.items():
        assert len(styles) > 0, f"No styles found in {folder}."
        for style in styles:
            assert (  # both in list of names and the library they are retrieved from hello
                style in plt.style.available and style in plt.style.library
            ), f"'{style}' not in available styles. Style in folder {folder}."
Check all styles are available in matplotlib.
scienceplots/tests/test_scienceplots.py