Agent Skills: react-testing-library

React Testing Library mechanics for testing React components and hooks — query selection, async handling, user interaction, assertions, provider setup, and the anti-patterns that make tests brittle. Use for any test that renders a React component or a hook, including choosing between getBy/queryBy/findBy, userEvent flows, waitFor usage, renderHook, custom render wrappers, and reviewing RTL tests for implementation-detail assertions.