What testing frameworks are available in Python? Auxiliary libraries?

In Python, there are several popular testing frameworks and auxiliary libraries:

• unittest — a built-in framework for unit testing in the standard library.
• pytest — a powerful and flexible framework with a convenient syntax, support for fixtures and plugins.
• nose2 — a continuation of the nose project, extending unittest capabilities.

Auxiliary libraries:

• mock (built into unittest since Python 3.3) — for creating stubs and mock objects.
• pytest-mock — a plugin for pytest that simplifies working with mocks.
• tox — for automating testing across different environments and Python versions.
• coverage.py — measuring code coverage with tests.

Example of a simple test with pytest:

import pytest

def add(a, b):
    return a + b


def test_add():
    assert add(2, 3) == 5

This set of tools allows for efficient writing and maintenance of tests in Python projects.