testing-react

name	testing-react
description	Stratégie de Tests React 19 + Compiler 1.0. Use when writing tests, reviewing test coverage, or setting up testing.
context	fork

Stratégie de Tests React 19 + Compiler 1.0

Versions : React 19.2+ | React Compiler 1.0 | Vitest 4.1+ | Playwright

Compatibilité React Compiler 1.0

React Compiler 1.0 (auto-memoization) est compatible avec tous les outils de tests React :

• Vitest + React Testing Library / Browser Mode : aucun changement requis
• Playwright : aucun changement requis
• MSW : aucun changement requis

Les tests restent comportementaux (pas d'implémentation testée), donc l'optimisation automatique du compilateur est transparente.

Note : Ne pas tester les optimisations du compilateur (memoization). Tester uniquement le comportement visible (UI, interactions, états).

Source : react.dev/blog/2025/10/07/react-compiler-1

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Stack recommandée 2026

Type	Outil	Usage
Unit/Composants	Vitest 4.1+ Browser Mode	Chromium/Firefox/WebKit natif
E2E	Playwright	Flows utilisateur complets
Mutation	Stryker	Qualité des tests (score >= 80%)

Abandonner : JSDOM (lourd, incomplet) et React Testing Library (remplacé par Playwright component testing).

Sources : Vitest 4, Playwright Component Testing, Stryker Mutator

Configuration Vitest 4 Browser Mode

// vitest.config.ts
import { defineConfig } from 'vitest/config';
import react from '@vitejs/plugin-react';

export default defineConfig({
  plugins: [react()],
  test: {
    browser: {
      enabled: true,
      name: 'chromium', // ou 'firefox', 'webkit'
      provider: 'playwright',
    },
    globals: true,
  },
});

Tests composants avec Vitest Browser Mode

// Button.test.tsx
import { render, screen, userEvent } from '@vitest/browser/context';
import { Button } from './Button';

test('handles click events', async () => {
  const handleClick = vi.fn();
  render(<Button onClick={handleClick}>Click me</Button>);
  
  await userEvent.click(screen.getByText('Click me'));
  
  expect(handleClick).toHaveBeenCalledOnce();
});

Source : Vitest Browser Mode Guide

Playwright Component Testing

Alternative supérieure à React Testing Library — browser réel, debugging visuel.

// Button.test.tsx
import { test, expect } from '@playwright/experimental-ct-react';
import { Button } from './Button';

test('handles click events', async ({ mount }) => {
  let clicked = false;
  
  const component = await mount(
    <Button onClick={() => { clicked = true; }}>
      Click me
    </Button>
  );
  
  await component.click();
  expect(clicked).toBe(true);
});

Source : Playwright Component Testing

Mutation Testing avec Stryker

# Installation
npm install -D @stryker-mutator/core @stryker-mutator/vitest-runner

# stryker.config.json
{
  "testRunner": "vitest",
  "coverageAnalysis": "perTest",
  "mutate": ["src/**/*.ts", "src/**/*.tsx"],
  "thresholds": { "high": 80, "low": 60, "break": 50 }
}

# Exécution
npx stryker run

Philosophie : "Coverage = quantité de code testé. Mutation score = qualité des tests."

Source : Stryker Mutator

React Server Components — Tests

// ProductList.test.tsx (RSC)
import { test, expect } from 'vitest';
import { ProductList } from './ProductList';

test('renders product list server component', async () => {
  const html = await ProductList({ category: 'books' });
  
  expect(html).toContain('Books');
  // RSC retourne du HTML, pas de DOM
});

Vitest Workspaces — Monorepo

// vitest.workspace.ts
export default defineWorkspace([
  {
    test: {
      name: 'unit',
      include: ['src/**/*.test.{ts,tsx}'],
    },
  },
  {
    test: {
      name: 'browser',
      browser: { enabled: true, name: 'chromium' },
      include: ['src/**/*.browser.test.{ts,tsx}'],
    },
  },
]);

Source : Vitest Workspaces

Property-based Testing

// fast-check pour générer des cas de test
import fc from 'fast-check';

test('calculateTotal is always positive', () => {
  fc.assert(
    fc.property(fc.array(fc.nat()), (prices) => {
      const total = calculateTotal(prices);
      return total >= 0;
    })
  );
});

Source : fast-check

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Voir @.claude/rules/07-testing.md pour principes transverses.