Skip to main content
Generaltrailofbits

mutation-testing

Configures mewt or muton mutation testing campaigns — scopes targets, tunes timeouts, and optimizes long-running runs. Use when the user mentions mewt, muton, mutation testing, or wants to configure or optimize a mutation testing campaign.

Stars
5,487
Source
trailofbits/skills
Updated
2026-05-27
Slug
trailofbits--skills--mutation-testing
View on GitHubRaw SKILL.md

// install — copy + paste into any project

mkdir -p .claude/skills && curl -fsSL https://raw.githubusercontent.com/trailofbits/skills/HEAD/plugins/mutation-testing/skills/mutation-testing/SKILL.md -o .claude/skills/mutation-testing.md

Drops the SKILL.md into .claude/skills/mutation-testing.md. Works with Claude Code, Cursor, and any agent that loads SKILL.md files from .claude/skills/.

Mutation Testing — Campaign Configuration (mewt/muton)

Note: muton and mewt share identical interfaces but target different languages — mewt for general-purpose languages (Rust, Solidity, Go, TypeScript, JavaScript), muton for TON smart contracts (Tact, Tolk, FunC). All examples use mewt commands, but they work exactly the same with muton. File names change accordingly: mewt.toml → muton.toml, mewt.sqlite → muton.sqlite.

When to Use

Use this skill when the user:

  • Mentions "mewt", "muton", or "mutation testing"
  • Needs to configure or optimize a mutation testing campaign
  • Wants to run mewt run and needs help getting set up first

When NOT to Use

Do not use this skill when the user:

  • Wants to analyze or report on completed campaign results
  • Asks about tests or coverage without mentioning mutation testing

Quick Start

Load workflows/configuration.md — a 5-phase guide from mewt init to a validated, ready-to-run campaign.

General question or unfamiliar command? Run mewt --help or mewt <subcommand> --help, then assist.

Reference Index

File Content
workflows/configuration.md 5-phase guide: init, scope, optimize, validate, run
references/optimization-strategies.md Per-file targeting, two-phase campaigns, mutation type filtering

Essential Commands

# Initialize and mutate
mewt init                    # Create mewt.toml and mewt.sqlite
mewt mutate [paths]          # Generate mutants without running tests
mewt run [paths]             # Run the full campaign

# Inspect configuration and scope
mewt print config            # View effective configuration
mewt print targets           # Table of all targeted files
mewt print mutations --language [lang]  # Available mutation types
mewt status                  # Mutant count and per-file breakdown

# Investigate specific mutants
mewt print mutants --target [path]   # All mutants for a file
mewt print mutants --severity high   # Filter by severity
mewt print mutant --id [id]          # View mutated code diff
mewt test --ids [ids]                # Re-test specific mutants

What Results Mean

  • Caught/TestFail: Tests detected the mutation (good)
  • Uncaught: Mutation survived — indicates untested logic
  • Timeout: Tests took too long, inconclusive
  • Skipped: A more severe mutant already failed on the same line