Testing React Components Guide

Philosophy Test behavior, not implementation. Write tests from the user's perspective. If you can't describe the test without referencing component internals, rethink the test.

Setup - Jest as the test runner - React Testing Library (RTL) for rendering and querying - user-event for simulating interactions

Query Priority 1. `getByRole` (most accessible) 2. `getByLabelText` (forms) 3. `getByText` (visible text) 4. `getByTestId` (last resort)

Common Patterns - Render, interact, assert - Use `screen.getByRole('button', { name: /submit/i })` - Use `waitFor` for async operations - Mock API calls, not the component itself