---

name: testing description: TDD/BDD testing principles. Use when writing tests, reviewing test coverage, setting up testing, or discussing test strategy and test architecture. context: fork files: ["/tests/", "/test/", "/tests/", "/spec/", ".test.", ".spec.", "Test.", "_test.*"]

Testing - Principes TDD/BDD (2026)

Principes universels de testing pour toutes les technologies du framework Claude-Craft.

Principes fondamentaux

• TDD Cycle: RED → GREEN → REFACTOR
• Couverture cible: >= 80%
• Pyramide: Unit (70%) > Integration (20%) > E2E (10%)
• Pattern: Arrange-Act-Assert (AAA)
• Nommage: Tests descriptifs expliquant le comportement

Outils recommandés 2026

Stack	Unit/Composants	E2E/Browser	Mutation Testing
JS/TS/React	Vitest 5 (Browser Mode stable)	Playwright	Stryker
PHP/Laravel/Symfony	Pest 5 (PHPUnit 13, PHP 8.4+, Browser Testing)	Playwright via Pest	Infection
Python	pytest 9.x + Ruff 0.17+	Playwright	Mutmut
Flutter	flutter_test + bloc_test 10+	Patrol 4	built-in
React Native	RNTL 14 + Jest	Maestro (ou Detox)	Stryker

Sources : Vitest Browser Mode, Pest 5 Upgrade Guide, Stryker Mutator

Stratégies 2026

Vitest 5 — Browser Mode stable

Abandonner JSDOM lourd. Chromium/Firefox/WebKit natifs.

// vitest.config.ts
import { defineConfig } from 'vitest/config';
import { playwright } from '@vitest/browser-playwright';

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

Source : Vitest Browser Mode

Mutation Testing — "Coverage ment, mutation scores disent la vérité"

Tester la qualité des tests. Mutation score >= 80%.

# Stryker (JS/TS/C#)
npx stryker run

# Infection (PHP)
vendor/bin/infection --min-msi=80

# Mutmut (Python)
mutmut run

Source : Stryker Mutator

Property-based Testing

Générer des tests à partir de propriétés invariantes.

// fast-check (JS/TS)
import fc from 'fast-check';

test('sorting preserves all elements', () => {
  fc.assert(
    fc.property(fc.array(fc.integer()), (arr) => {
      const sorted = [...arr].sort();
      return sorted.length === arr.length;
    })
  );
});

Source : fast-check

Pest 5 — Browser Testing intégré

// Pest 5 avec Playwright natif
test('user can login', function () {
    visit('/login')
        ->fill('email', 'alice@example.com')
        ->fill('password', 'secret')
        ->click('Login')
        ->assertPathIs('/dashboard');
});

Source : Pest Browser Testing

Vitest Projects — Monorepos

workspace est déprécié depuis Vitest 3.2 au profit de projects.

// vitest.config.ts
import { defineConfig } from 'vitest/config';
import { playwright } from '@vitest/browser-playwright';

export default defineConfig({
  test: {
    projects: [
      'packages/*', // Unit tests (un vitest.config par package)
      {
        test: {
          name: 'browser',
          include: ['e2e/**/*.test.ts'],
          browser: { enabled: true, provider: playwright(), instances: [{ browser: 'chromium' }] },
        },
      },
    ],
  },
});

Source : Vitest Projects

BDD — un outil Gherkin par écosystème

Écosystème	Outil
JS/TS	Cucumber.js (@cucumber/cucumber)
PHP/Symfony	Behat 4.x
Python	pytest-bdd

Pour l'E2E mobile, Maestro (flows YAML) couvre React Native, Flutter et natif ; Patrol (Flutter) et Detox (React Native) restent des alternatives intégrées à leur framework.

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Voir @.claude/references/base/testing.md pour documentation complète.