@pytest.mark.parametrize('invalid_dt', ['2013', '01/2013', '12:00:00', '1/1/1/1', 'this_is_not_a_datetime', '51a', 9, datetime(2011, 1, 1)])
def test_guess_datetime_format_invalid_inputs(invalid_dt):
    assert (parsing._guess_datetime_format(invalid_dt) is None)
@pytest.mark.parametrize('invalid_dt', ['2013', '01/2013', '12:00:00', '1/1/1/1', 'this_is_not_a_datetime', '51a', 9, datetime(2011, 1, 1)])
def test_guess_datetime_format_invalid_inputs(invalid_dt):
    assert (parsing._guess_datetime_format(invalid_dt) is None)