def test_time_difference_hour():
    minute = 60
    forecaster = Forecaster('2019-05-04', '2019-04-21', 5)
    assert forecaster.get_time_difference('13:30:00',
                                          '14:30:00') == 60 * minute
def test_time_difference_none():
    forecaster = Forecaster('2019-05-04', '2019-04-21', 5)
    assert forecaster.get_time_difference(None, 5) == 0