# React Testing

> Testing strategies with RTL and Jest/Vitest. Use when writing React component tests with React Testing Library, Jest, or Vitest. (triggers: **/*.test.tsx, **/*.spec.tsx, render, screen, userEvent, expect)

- Skill: `hoangnguyen0403/react-testing-2` (Agent Skill)
- Install (CLI): `npx skillmds@latest add hoangnguyen0403/react-testing-2`
- Raw SKILL.md: https://api.skillmd.com/api/skills/hoangnguyen0403/react-testing-2/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Web & Frontend
- Author: HoangNguyen0403 (https://skillmd.com/u/hoangnguyen0403)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/hoangnguyen0403/react-testing-2

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# React Testing

## **Priority: P2 (MAINTENANCE)**

Reliable tests focusing on user behavior.

## Implementation Guidelines

- **Standards**: Use **React Testing Library (RTL)** with **Vitest or Jest**. Follow the **Arrange-Act-Assert (AAA)** pattern.
- **Selection**: Prefer **`getByRole`** / **`findByRole`** to test accessibility. Use **`data-testid`** only as a fallback for complex UI.
- **Interactions**: Use **`userEvent` (async)** instead of `fireEvent` to better simulate browser events (e.g., `await user.click(element)`).
- **Asynchrony**: Use **`await screen.findBy*`** for elements that appear later. Use **`waitFor(() => ...)`** for complex non-element updates.
- **Networking**: Mock all API calls with **Mock Service Worker (MSW)**. **Never call real APIs** in unit/integration tests.
- **Architecture**: **Test behavior**, not implementation. Avoid checking internal `state` or `props`. Ensure **100% of P0 flows** are covered.
- **Mocks**: **Mock expensive third-party libraries** (e.g., `framer-motion`, `react-router`) or heavy assets to speed up tests.
- **Visuals**: Use **Snapshot testing** sparingly for stable, small UI components. **Manual a11y checks** with `jest-axe`.

## Anti-Patterns

- **No Shallow Rendering**: Render full tree.
- **No Testing Implementation Details**: Don't check `component.state`.
- **No Wait**: Use `findBy`, avoid `waitFor` if possible.

## References

See [references/REFERENCE.md](references/REFERENCE.md) for MSW API mocking, Context testing, form testing, and React Router patterns.

## Code

```tsx
test('submits form', async () => {
  const user = userEvent.setup();
  render(<LoginForm />);

  await user.type(screen.getByLabelText(/email/i), 'test@test.com');
  await user.click(screen.getByRole('button', { name: /login/i }));

  expect(await screen.findByText(/welcome/i)).toBeInTheDocument();
});
```