Testing class and methods

Pytest allows us to write our tests in an object oriented fashion as well. In that case we need to create one or more classes called ClassSomething in the files that are called test_something.py. In the classes there have to be methods called test_something that are similar to the function in the previous case.

import mymath

class TestMath():
    def test_math(self):
        assert mymath.add(2, 3)  == 5
        assert mymath.div(6, 3)  == 2
        assert mymath.div(42, 1) == 42
        assert mymath.add(-1, 1) == 0

We run the tests the same way.

$ pytest test_mymath_with_pytest_class.py
=========================================== test session starts ============================================
platform linux -- Python 3.13.7, pytest-9.0.2, pluggy-1.6.0
rootdir: /home/gabor/github/code-maven.com/python.code-maven.com
configfile: pyproject.toml
plugins: anyio-4.12.0, cov-7.0.0
collected 1 item

test_mymath_with_pytest_class.py .                                                                   [100%]

============================================ 1 passed in 0.07s =============================================

Shall we use OOP for writing tests?

Test are supposed to be a lot less complex than our real code. Therefore in general I discourage using OOP in the tests.