genotoxic
Graph-informed mutation testing triage. Parses codebases with Trailmark, runs mutation testing and necessist, then uses survived mutants, unnecessary test statements, and call graph data to identify false positives, missing test coverage, and fuzzing targets. Use when triaging survived mutants, analyzing mutation testing results, identifying test gaps, finding fuzzing targets from weak tests, running mutation frameworks (including circomvent and cairo-mutants), or using necessist.
npx skills add trailofbits/skills --skill genotoxic --agent claude-code
Same command for any agent — swap --agent for codex, cursor, copilot.
Weekly change comes from our own snapshots, not the repository page — it measures attention, not adoption.
# Genotoxic Combines mutation testing and necessist (test statement removal) with code graph analysis to triage findings into actionable categories: false positives, missing unit tests, and fuzzing targets. ## When to Use - After mutation testing reveals survived mutants that need triage - Identifying where unit tests would have the highest impact - Finding functions that need fuzz harnesses instead of unit tests - Prioritizing test improvements using data flow context - Filtering out harmless mutants from actionable ones - Finding unnecessary test statements that indicate weak assertions (necessist) ## When NOT to Use - Codebase has no existing test suite (write tests first) - Pure documentation or configuration changes - Single-file scripts with trivial logic ## Prerequisites - **trailmark** installed — if `uv run trailmark` fails, run: ```bash uv pip install trailmark ``` **DO NOT** fall back to "manual verification" or "manual analysis" as a substitute for running trailmark. Install it first. If installation fails, report the error instead of switching to manual analysis. - A **mutation testing framework** for the target language — if the framework command fails (not found, not
- When to Use
- When NOT to Use
- Prerequisites
- Rationalizations to Reject
- Quick Start
- Workflow Overview
- Decision Tree
- Phase 1: Build Code Graph and Run Pre-Analysis
- Phase 2: Run Mutation Testing
- Phase 2b: Run Necessist (Optional)
- Phase 3: Triage Findings
- Quick Classification (Mutation Testing)
- Quick Classification (Necessist)
- Graph Queries for Triage
uv pip install trailmark
uv run trailmark analyze --language auto --summary {targetDir}
uv run mutmut run --paths-to-mutate {targetDir}/src
uv run mutmut results
necessist
Auto-detect framework
Or target specific test files
necessist tests/test_parser.rs
Export results
necessist --dumpWhat does the genotoxic skill do?
Graph-informed mutation testing triage. Parses codebases with Trailmark, runs mutation testing and necessist, then uses survived mutants, unnecessary test statements, and call graph data to identify false positives, missing test coverage, and fuzzing targets. Use when triaging survived mutants, analyzing mutation testing results, identifying test gaps, finding fuzzing targets from weak tests, running mutation frameworks (including circomvent and cairo-mutants), or using necessist.
How do I install it?
Run `npx skills add trailofbits/skills --skill genotoxic --agent claude-code` — it drops the skill into your project so the agent can pick it up. Swap the --agent value for codex, cursor or copilot if you use one of those.
Where does this skill come from?
From trailofbits/skills, a repository with 6,426 stars. We read it straight from the repository tree rather than a submitted listing, so what you see here is what is actually published.
Is a popular skill a good skill?
Not necessarily. Stars measure attention, not adoption — a repository can trend for a week and be abandoned. That is why we show the weekly change from our own snapshots next to the total, instead of a single flattering number.