Pytest - the assert statement

The assert statement in Python is used for debugging and testing purposes. It allows us to check if a condition is True, and if it's not, it will Raise an Exception called AssertionError. This can be very helpful in writing unit tests to verify if the expected results match the actual results.

assert condition, message

Check it out

• Let's see below addition.py and its test case.

addition.py

def addition(x, y):
    return x + y

test_file.py

from addition import addition

def test_addition_int():
    assert addition(4, 5) == 9
    assert addition(12, 2) == 14

def test_addition_str():
    assert addition('a', 'b') == 'ab'

• to test it out, run

docker build -t pytest-assertion docs/learning-python/unit-testing/assertion/ && docker run pytest-assertion

Result

============================= test session starts ==============================
platform linux -- Python 3.9.19, pytest-8.2.0, pluggy-1.5.0
rootdir: /test
collected 2 items

test_file.py ..                                                          [100%]

============================== 2 passed in 0.01s ===============================