def test_is_leap_year_if_divisible_by_400(self):
year = Year(1600)
self.assertTrue(year.is_leap())
def test_not_leap_year_if_divisible_by_100_but_not_by_400(self):
year = Year(1900)
self.assertFalse(year.is_leap())
def test_not_leap_year_if_not_divisible_by_4(self):
year = Year(1997)
self.assertFalse(year.is_leap())
