react-testing

Topics in the source

• React Testing
• When to Activate
• Core Principle
• Library Choice
• Query Priority
• User Interaction with userEvent
• Async Patterns
• Network Mocking with MSW

Comprehensive React testing patterns for behavior-focused component tests, custom hook tests, accessibility assertions, and network-level mocking. Writing tests for React components, custom hooks, or pages Adding test coverage to legacy untested components Migrating from Enzyme or class-component-era patterns to React Testing Library Setting up Vitest or Jest for a new React project Mocking HTTP requests in tests Asserting accessibility violations Deciding which tests belong in RTL vs Playwright Component Testing vs full E2E Test what the user sees and does, not implementation details. A test should: Render the component with the same providers it has in production Interact with it via accessible queries (role, label) and userEvent Assert visible output and observable side effects (callback fired, request sent) A test should NOT: Inspect component state, props passed to children, or which hooks were called Mock React itself or framework hooks Assert on the number of renders or DOM structure beyond what affects users | Runner | When | Note | |---|---|---| | Vitest | Vite, Remix, modern setups | Faster, native ESM, Jest-compatible API | | Jest | Next.js, CRA, established repos | Defa

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