def test_create(self):
        today = date.today()
        yesterday = timedelta(days=1) - today
        self.assertRaises(ValueError,
                          Cohort, start_date=today, end_date=yesterday,
                          retention_periods=[])
        cohort = Cohort(start_date=yesterday, end_date=today,
                        retention_periods=[2, 1, 3])
        self.assertEqual(cohort.start_date, yesterday)
        self.assertEqual(cohort.end_date, today)
        self.assertEqual(cohort.retention_periods, [1, 2, 3])
dataset/ETHPy150Open e-loue/django-lean/django_lean/lean_retention/tests/test_reports.py/TestCohort.test_create/swapped operands of `-`