Test Automator

This one gives Claude the knowledge to write and maintain automated tests across the testing pyramid, from unit tests up through E2E. It activates when you ask to write tests or improve coverage, and comes loaded with patterns for Jest, Playwright, pytest, and others. The source material is genuinely thorough: you get the Arrange-Act-Assert pattern, coverage targets (80% lines, 75% branches), practical examples of mocking, and real code snippets for each test type. What I like is it pushes you toward testing behavior instead of implementation details, which is the right instinct but easy to forget when you're just trying to hit coverage numbers. Includes boilerplate generation scripts and framework-specific references.