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Analyze surviving mutants from a mutation testing run and write targeted unit tests to kill them. Re-runs mutations to confirm kills.
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Based on SOC occupation classification
Analyze changed code for complex, under-tested functions using CRAP scoring; produce ranked refactor and test recommendations.
Validate strict DAE quality gates after implementation-affecting changes, require machine-readable evidence, and write the quality-gate summary before completion or release.
This skill should be used when the user asks to "run mutation testing", "mutate my code", "kill mutants", "check test quality", "find surviving mutants", "verify test effectiveness with mutations", "run stryker", "run mutmut", "run pitest", "set up mutation testing", "how good are my tests", "are my tests catching bugs", or mentions mutation testing, mutation score, or mutant survival in the context of testing. It adds a third validation layer to the ATDD workflow: after acceptance tests verify WHAT and unit tests verify HOW, mutation testing verifies that tests actually catch bugs.
This skill should be used when the user asks to "build a feature", "implement a feature", "add functionality", "start development", "write acceptance tests", "write specs", "use ATDD", "use TDD with acceptance tests", or begins any feature implementation work. Also available as the atdd plugin's main skill. Enforces the Acceptance Test Driven Development workflow: write Given/When/Then specs before code, generate a project-specific test pipeline, and maintain two test streams.
This skill should be used when the user asks to "build a feature with a team", "use ATDD with agents", "create an ATDD team", "set up a team for ATDD", "orchestrate agents for ATDD", "use team-based development", "coordinate agents for feature development", "run the ATDD workflow with teammates", "add ATDD to my team", "extend my team with ATDD", "join the team with ATDD agents", "add spec-writer and reviewer to the team", or "add ATDD roles to the existing team". It orchestrates a six-phase ATDD workflow — spec writing, spec review, pipeline generation, implementation, refine, verify & harden — spawning a fresh agent per phase so no agent erodes across a long-running feature.
Use as a thin compatibility skill when the user asks for the old mutate command; delegate to atdd-mutate for mutation testing and differential mutation workflow.
| name | kill-mutants |
| description | Analyze surviving mutants from a mutation testing run and write targeted unit tests to kill them. Re-runs mutations to confirm kills. |
| arguments | [{"name":"ARGUMENTS","description":"Optional mutant IDs or file path to focus on (e.g., \"src/auth.ts\" or \"1,3,5\" for specific mutant IDs)","required":false}] |
Analyze surviving mutants and write tests to kill them.
Read the most recent mutation testing report/results.
If no report exists, ask the user to run the atdd-mutate skill first.
List all surviving mutants. For each, determine:
If $ARGUMENTS specifies a file or mutant IDs, filter to only those survivors.
For each non-equivalent survivor: a. Write a targeted unit test that:
After writing all new tests, re-run mutation testing with atdd-mutate to confirm:
Report the updated mutation score and remaining survivors.
For any remaining equivalent mutants, document them:
Equivalent mutants (safe to ignore):
- src/utils.ts:42 — `x + 0` → `x + 1` (no behavioral change)