Tox

tox is built to automate and standardize how Python code is tested. It is a general-purpose command-line tool for managing virtual environments and running tests, creating isolated environments, installs your package into each one and runs your tests there, making it a staple of Python project workflows. It belongs to a broader effort to simplify packaging, testing and releasing Python software, together with pytest and devpi.

Typical uses are checking that a package builds and installs correctly under different Python implementations, versions or dependency sets, running tests in every environment with the test tool of your choice, and acting as a front end for continuous integration servers so that CI configuration and local shell commands stay in sync with much less boilerplate. Topics reference virtualenv, venv and GitHub Actions.

tox is written in Python and licensed under MIT. It runs on developer machines and in CI pipelines, so nothing needs hosting. It suits maintainers of Python libraries and applications who need a repeatable way to test across versions.