Using assertRaises unit test for date comparison

March 16, 2022

I’m trying to use assertRaises(ValueError) in Python to return an error when the start date of my code is after the end date.

class TestDateUtils(unittest.TestCase):
def test_date_range(self):
     start_date = datetime.date(2020, 1, 1)
     end_date = datetime.date(2020, 1, 1)
     expected = start_date < end_date
     actual = start_date > end_date

    with self.assertRaises(ValueError):
        if actual:
            raise ValueError
        else:
            expected
            print("all fine")

I’m new to Python (and this is probably nowhere near the correct way to write this).
Would anyone know the correct syntax for trying to produce this end result? I just want to raise a value error if my start date is after the end date.

>Solution :

The purpose of assertRaises is to test that an exception is raised by the code under test in a certain set of circumstances; it is not for raising a value error.

If you want to assert in a test case that one value is less than another, you can use assertLess or assertLessEqual.

E.g.