claude-skill-testweaver

A Claude Code skill that finds surviving gremlins mutations in a Go package and generates targeted tests to catch them. Each generated test is validated end-to-end (baseline → compile → clean → mutate → revert) before it’s committed on a new branch with a PR.

Install

npx claude-skill-testweaver

You’ll be asked whether to install for your user or the current project:

Scope	Path	When to use
User-level	~/.claude/skills/testweaver/	Available in every Claude Code session.
Project-level	./.claude/skills/testweaver/	Pinned to one repo, checked into source control if you want.

Skip the prompt with a flag:

npx claude-skill-testweaver --user
npx claude-skill-testweaver --project
npx claude-skill-testweaver --force        # overwrite without asking
npx claude-skill-testweaver update         # reinstall over existing
npx claude-skill-testweaver uninstall      # remove

Requirements

The skill shells out to these tools — install them before running it:

• gremlins — Go mutation tester
• gh — GitHub CLI (for opening PRs)
• jq — JSON parsing
• A working Go toolchain

Usage

Inside Claude Code, after installing:

/testweaver github.com/acme/repo/pkg/foo
/testweaver github.com/acme/repo/pkg/foo 3   # attempt up to 3 mutations this run

The skill will:

1. Run gremlins unleash against the package.
2. Pick mutations that survived (status = LIVED).
3. Generate a _test.go for each, validating it catches the mutation on mutated code and passes on clean code.
4. Commit the test files on a new branch and open a PR via gh.

Full skill documentation lives in skill/SKILL.md.

Local development

# dry-run the installer against a scratch dir
mkdir /tmp/tw-scratch && cd /tmp/tw-scratch
node /path/to/this/repo/bin/cli.js --project
ls .claude/skills/testweaver/

# verify packaging
cd /path/to/this/repo
npm pack --dry-run

Publishing

Tag a release (vX.Y.Z) and the GitHub Actions workflow publishes to npm. Requires NPM_TOKEN set as a repo secret.

License

MIT — see LICENSE.