unittest and pytest

Scenario: The project needs an automated command that finds and runs every test.

New words, in plain English

• Test runner - a tool that discovers and executes tests
• unittest - Python's built-in class-based testing framework
• pytest - a popular runner supporting plain assert tests
• Discovery - finding tests by naming conventions

Run built-in tests with python -m unittest; run pytest with python -m pytest. Pytest rewrites asserts for helpful reports and can also run many unittest suites.

Analogy: A Python program is like a clear set of instructions for a careful helper: names label things, indentation groups steps, and errors explain where the helper became confused.

A small, real example

import unittest
class AddTests(unittest.TestCase):
    def test_add(self):
        self.assertEqual(2 + 3, 5)

# Equivalent pytest style:
def test_add(): assert 2 + 3 == 5

Tip: Invoke tools through python -m ... to use the active environment's interpreter.

Goal: Practice this idea in the py-pytest-suite challenge at /labs/python. Fix the broken program, run it yourself, then use check to prove the real end state.