My defaultOpen sourceTest quality

Stryker mutation testing

Tests for your tests. It mutates the code and checks your suite notices.

When agents write most of the code and the tests, mutation testing is how I know the tests are worth anything.

Use it when

Agent-written code: it proves the tests actually catch bugs.

Pricing

Free.

Where it fits

Building with AI agents: Pick 04.
Proves the tests catch bugs.

Sources

Stryker

Last reviewed 18 October 2026 by Nicolas Dao

Also in Build and test

Default Claude Code: AI coding agent
Default GitHub: Code hosting
Default Node.js (plain JavaScript): Language
Default OpenAI Codex: Second AI agent
Default Playwright, Vitest, pytest: Testing
Skip TypeScript
Never GitLab, Bitbucket and Atlassian

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