def test_get_period_intersection(self): period_1 = Period('2007-01-01', '2008-01-01') period_2 = Period('2007-07-01', '2008-07-01') period_3 = Period('2007-10-01', '2007-11-01') period_4 = Period('2001-07-01', '2002-07-01') self.assertEqual(period_1, period_1.get_intersection(period_1)) self.assertEqual(period_2, period_2.get_intersection(period_2)) self.assertEqual(Period('2007-07-01', '2008-01-01'), period_1.get_intersection(period_2)) self.assertEqual(Period('2007-07-01', '2008-01-01'), period_2.get_intersection(period_1)) self.assertEqual(period_3, period_1.get_intersection(period_3)) self.assertTrue(period_1.get_intersection(period_4) is None)