Announcing pytest-gremlins v1.3.0

Mutation Testing That Actually Fits Into Your Workflow Mutation testing tools (mutmut, Cosmic Ray, MutPy) exist, but most teams don't use them in practice. The bottleneck is runtime: waiting 20 minutes per mutation run makes the feedback loop too long to fit inside a normal TDD cycle. pytest-gremlins v1.3.0 ships today with UX fixes and correctness patches that were blocking production workflows. What Is pytest-gremlins? pytest-gremlins is a mutation testing plugin for pytest. It injects small code modifications into your source (flipping > to >= , changing and to or , negating return values), then runs your tests to see which mutations survive. Survivors indicate code that is covered but not validated: the tests execute it, but no assertion distinguishes the mutated behavior from the original. Four mechanisms drive its speed: Mutation switching : instrument the code once with all mutations embedded, then toggle active mutations via environment variable. No file rewrites, no module rel