unittest vs pytest

Free and open source

Free and open source

Free and open source. You pay in engineering time and CI minutes.

Free and open source. You pay in engineering time and CI minutes.

Everything, self-hosted

Everything, self-hosted

Widely used

Python Software Foundation · since 2001

Category standard

pytest-dev · since 2004

• In the standard library — nothing to install or vet.
• unittest.mock is excellent and used almost universally in Python.
• Familiar to anyone coming from JUnit or NUnit.

• Fixtures are the best dependency-injection model in any test framework, and they compose cleanly.
• Assertion introspection produces genuinely useful failure output from a plain assert.
• Vast plugin ecosystem — pytest-xdist, pytest-cov, pytest-asyncio, pytest-django.

• Verbose compared to pytest for the same coverage.
• No parametrisation or fixture composition worth the name.
• Most teams run unittest tests through pytest anyway.

• Fixture scope and ordering become genuinely hard to reason about in large suites.
• The magic that makes simple cases elegant makes complex cases opaque.
• Python only.

Standard-library-only environments and codebases that already use it.

Essentially every Python project.