Testing demo: pytest using classes - failure

Here too we can add additional test-functions to the same test-class. Executing pytest will print .F indicating one passing test-function and one failing test function. We'll get detailed explanation where the failure happened.

The exit-code will be different from 0 helping the CI systems and any other external system to know that the tests have failed.

import mymath

class TestMath():
    def test_math(self):
        assert mymath.add(2, 2) == 4

    def test_more_math(self):
        assert mymath.add(3, 3) == 6

============================= test session starts ==============================
platform linux -- Python 3.8.2, pytest-5.4.2, py-1.8.1, pluggy-0.13.1
rootdir: /home/gabor/work/slides/python/examples/testing-demo
plugins: flake8-1.0.6
collected 2 items

test_with_pytest_class_failure.py .F                                     [100%]

=================================== FAILURES ===================================
___________________________ TestMath.test_more_math ____________________________

self = <test_with_pytest_class_failure.TestMath object at 0x7fcddf82b7c0>

    def test_more_math(self):
>       assert mymath.add(3, 3) == 6
E       assert 9 == 6
E        +  where 9 = <function add at 0x7fcddf82a0d0>(3, 3)
E        +    where <function add at 0x7fcddf82a0d0> = mymath.add

test_with_pytest_class_failure.py:8: AssertionError
=========================== short test summary info ============================
FAILED test_with_pytest_class_failure.py::TestMath::test_more_math - assert 9...
========================= 1 failed, 1 passed in 0.03s ==========================

$ pytest test_with_pytest_class_failure.py
$ echo $?
1

> pytest test_with_pytest_class_failure.py
> echo %ERRORLEVEL%
1