Skills 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.

install

source · Clone the upstream repo

git clone https://github.com/trailofbits/skills

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/trailofbits/skills "$T" && mkdir -p ~/.claude/skills && cp -r "$T/plugins/mutation-testing/skills/mutation-testing" ~/.claude/skills/trailofbits-skills-mutation-testing && rm -rf "$T"

manifest: plugins/mutation-testing/skills/mutation-testing/SKILL.md

source content

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

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