pytest

pytest is a Python testing framework that makes it easy to write small, readable tests and scales to complex functional testing of applications and libraries.

Tests are plain functions whose names start with test_, using the standard assert statement; pytest discovers them automatically and reports detailed information on failing assertions. Fixtures, parametrisation and a large ecosystem of plugins extend the framework for different kinds of projects.

pytest is distributed under the MIT licence and actively developed on GitHub; version 9.1.1 was released in June 2026.