def METHOD_NAME():
    """
    clear os.environ, and restore it after the test runs
    """
    # for use whenever you expect code to edit environment variables
    old_env = os.environ.copy()
    class EnvironDict(dict):
        def __setitem__(self, key, value):
            assert isinstance(value, str)
            super().__setitem__(key, value)
    os.environ = EnvironDict()
    yield
    os.environ = old_env