python-testing

Build test infrastructure for a Python package that stays trustworthy under pressure: pytest configuration the installed pytest actually reads, branch coverage with a gate proven to fail, Hypothesis and mutation testing as backstops against tests that execute code without checking it, and multi-version runs. The failure this skill prevents is green-but-meaningless — gates that silently pass, config tables that are silently ignored, and suites edited (by humans or agents) until they stop proving anything.

When NOT to use