tox
Domain: Testing Quality
🎯 Motivation
tox automates testing across multiple Python versions and environments in isolated virtualenvs. It catches compatibility bugs before users hit them, which is essential for libraries supporting Python 3.9 through 3.13.
📋 Concrete Example
A tox.ini file lists py39, py310, py311 as environments. Running tox creates three virtualenvs and runs the full test suite in each, reporting which versions pass or fail.
🔗 Analogy
tox is like a quality inspector who tests a product on different machine models. A phone case must fit every phone model, not just the latest one.