Nox

What Nox is

Nox is a command-line tool for automating tests across multiple Python environments. A project defines its Nox sessions in a standard Python file named noxfile.py. For each session, Nox can create a virtual environment, install specified dependencies, and run commands in order. Sessions can target multiple Python interpreters, each with a separate virtual environment, and can be parameterized to use different dependency or database values. Nox supports venv, uv, conda, mamba, micromamba, and virtualenv environment backends. Tags let users organize sessions and choose which ones to run. Helpers can load dependencies from pyproject.toml files and PEP 723 scripts. Nox runs on Linux, macOS, and Windows, and can be installed with pip or pipx. For continuous integration, its tutorial documents the wntrblm/nox GitHub Action for installing Nox and selecting Python versions. The project describes Nox as focused on Python testing and recommends other tools when broader task execution is needed. It is free and open-source. Its homepage says more than 3,000 projects use Nox, and lists community maintainers and contributors, with contributor payments through Open Collective.

Who it suits

Nox suits Python developers who want repeatable test sessions across Python interpreters and dependency configurations. It can also fit projects that need to run those sessions in continuous integration using the documented GitHub Action.

Getting started

1. Install Nox with pip or pipx.
2. Add a noxfile.py to configure project sessions.
3. Set the Python interpreters, dependencies, and commands for sessions.
4. Run the sessions you want, using tags to select them if needed.
5. For continuous integration, follow the tutorial's use of the wntrblm/nox GitHub Action.

Verdict

Choose Nox for automating Python tests across interpreters, dependency sets, or database values, with sessions configured in Python. Look elsewhere when your task execution needs go beyond its stated focus on Python testing.