#Pytest
8 posts
Python Testing #7: Running Tests in CI — People Forget, Machines Don't
Build a CI workflow that runs pytest automatically with GitHub Actions. Covers uv caching, a Python version matrix, coverage comments on PRs, pre-commit, and separating slow tests to wrap up the series.
Python Testing #6: Test Design — Good Tests and How to Read Coverage
Test design fundamentals from the AAA pattern and behavior-driven tests to test double terminology, dealing with flaky tests, and reading pytest-cov coverage numbers the right way.
Python Testing #5: Testing the Outside World — Files, HTTP, Databases, and Web Frameworks
A test that mocks everything guarantees nothing about real behavior. A strategy for testing the outside world: write real files with tmp_path, block only the network boundary with respx, and reset databases with transaction rollbacks.
Python Testing #4 mock and monkeypatch: Controlling What You Can't Control
How to pin down dependencies that change on every run — time, randomness, external APIs — with monkeypatch and unittest.mock, including the patch-path trap and where over-mocking begins.
Python Testing #3 parametrize and Markers: Multiply Cases, Run Selectively
How to collapse input-only test variations into one case table with @pytest.mark.parametrize, and run only the tests you want using skip, skipif, xfail, custom markers, and the -m and -k options.
Python Testing #2 Fixtures: Injecting Setup and Teardown
How to inject test setup code with @pytest.fixture — yield teardown, scope trade-offs, sharing via conftest.py, and built-in fixtures like tmp_path.
Python Testing #1 Getting Started with pytest: Why One assert Is All You Need
How to install pytest and write your first test with a single assert — plus how it differs from unittest, how to read failure output, and the test discovery rules.
Modern Python in Practice #6: Testing and Deployment — pytest, Docker, Railway/Fly
FastAPI integration tests with pytest + httpx, isolation via dependency overrides, multi-stage Docker builds, and cloud deployment to Railway/Fly.