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Minimal example math_func.py

When excecuted, pytest looks for functions which names start with "test_" and automatically runs them ...

import pytest

def inc(x):
    return x + 1

def test_answer():
    assert inc(3) == 4

Run example: (env) PS C:\Users\cweic\code\playground4> pytest .\math_func.py

If assertion of test function equals true, pytest will the following message:

============================================================ 1 passed in 0.04s ============================================================= 
(env) PS C:\Users\cweic\code\playground4> pytest .\math_func.py
=========================================================== test session starts ============================================================
platform win32 -- Python 3.9.5, pytest-6.2.4, py-1.10.0, pluggy-0.13.1
rootdir: C:\Users\cweic\code\playground4
collected 1 item                                                                                                                             

math_func.py .  
============================================================ 1 passed in 0.03s ============================================================= 
(env) PS C:\Users\cweic\code\playground4> 

In case the assertion equals false, the output looks like:

math_func.py F                                                                                                                        [100%]

================================================================= FAILURES ================================================================= 
_______________________________________________________________ test_answer ________________________________________________________________ 

    def test_answer():
>       assert inc(3) == 5
E       assert 4 == 5
E        +  where 4 = inc(3)

math_func.py:9: AssertionError
========================================================= short test summary info ========================================================== 
FAILED math_func.py::test_answer - assert 4 == 5
============================================================ 1 failed in 0.15s =============================================================
(env) PS C:\Users\cweic\code\playground4>