def METHOD_NAME(self):
    # custom seasons with missing months raises an error?
    seasons = ("djfm", "amjj")
    for func in (
        ccat.add_season,
        ccat.add_season_year,
        ccat.add_season_number,
    ):
        with self.assertRaises(ValueError):
            func(self.cube, "time", name="my_category", seasons=seasons)