chunk-testing-gaps
Chunk Mutate Skill
Perform mutation testing on the current codebase to find gaps in test coverage.
Goal
Perform mutation testing on this codebase. A mutation is a small, deliberate change to production code that mimics a realistic bug a human might introduce. A mutant is the resulting modified codebase. If the test suite catches the bug (tests fail), the mutant is killed. If tests still pass, the mutant survives — exposing a gap in test coverage.
The objective is to find as many surviving mutants as possible, prioritised by risk.
Prerequisites
This prompt expects to be run in the context of a local clone of a VCS project. If that is not the case, stop and explain why you cannot proceed.
Before any testing, ensure local dependencies are running (docker compose up -d or equivalent). On compose failure, check whether containers from another project are occupying ports and kill them.
Stage 2 runs mutants on chunk sidecars, which needs validation.sidecarImage set in .chunk/config.json. Check it with cat .chunk/config.json. If it is missing, stop and tell the user to run the one-time setup in the chunk-sidecar skill (Step 3) first — booting a fresh unconfigured sidecar per mutant is slow enough to make the whole run impractical.