Localization Testing

Localization & Internationalization Testing

Browser engine

Browser-driven locale checks (RTL layout diffs, language-switching flows, locale-specific screenshots) should go through the qe-browser fleet skill. Example:

vibium go "$BASE_URL?lang=ar"  # Arabic, RTL
vibium wait load
node .claude/skills/qe-browser/scripts/visual-diff.js --name homepage-ar-rtl
vibium go "$BASE_URL?lang=ja"  # Japanese, CJK text expansion
node .claude/skills/qe-browser/scripts/visual-diff.js --name homepage-ja

See .claude/skills/qe-browser/SKILL.md for the full reference.

Quick i18n Checklist:

• All user-facing strings externalized
• No hardcoded text in code
• Date/time/currency formatted per locale
• RTL languages flip layout correctly
• Unicode characters display properly

Critical Success Factors:

• Don't hardcode strings - externalize everything
• Test with real speakers, not just translation files
• RTL requires mirrored UI layout

Quick Reference Card

When to Use

• Launching in new markets
• Adding language support
• Before international releases
• After UI changes

Translation Coverage Testing

test('all strings are translated', () => {
  const enKeys = Object.keys(translations.en);
  const frKeys = Object.keys(translations.fr);
  const esKeys = Object.keys(translations.es);

  // All locales have same keys
  expect(frKeys).toEqual(enKeys);
  expect(esKeys).toEqual(enKeys);
});

test('no missing translation placeholders', async ({ page }) => {
  await page.goto('/?lang=fr');
  const text = await page.textContent('body');

  // Should not see placeholder keys
  expect(text).not.toContain('translation.missing');
  expect(text).not.toMatch(/\{\{.*\}\}/); // {{key}} format
});

Date/Time/Currency Formats

test('date formats by locale', () => {
  const date = new Date('2025-10-24');

  expect(formatDate(date, 'en-US')).toBe('10/24/2025');
  expect(formatDate(date, 'en-GB')).toBe('24/10/2025');
  expect(formatDate(date, 'ja-JP')).toBe('2025/10/24');
});

test('currency formats by locale', () => {
  const amount = 1234.56;

  expect(formatCurrency(amount, 'en-US', 'USD')).toBe('$1,234.56');
  expect(formatCurrency(amount, 'de-DE', 'EUR')).toBe('1.234,56 €');
  expect(formatCurrency(amount, 'ja-JP', 'JPY')).toBe('¥1,235');
});

RTL (Right-to-Left) Testing

test('layout flips for RTL languages', async ({ page }) => {
  await page.goto('/?lang=ar'); // Arabic

  const dir = await page.locator('html').getAttribute('dir');
  expect(dir).toBe('rtl');

  // Navigation should be on right
  const nav = await page.locator('nav');
  const styles = await nav.evaluate(el =>
    window.getComputedStyle(el)
  );
  expect(styles.direction).toBe('rtl');
});

test('icons/images appropriate for RTL', async ({ page }) => {
  await page.goto('/?lang=he'); // Hebrew

  // Back arrow should point right in RTL
  const backIcon = await page.locator('.back-icon');
  expect(await backIcon.getAttribute('class')).toContain('rtl-flipped');
});

Unicode Character Support

test('supports unicode characters', async ({ page }) => {
  // Japanese
  await page.fill('#name', '山田太郎');
  await page.click('#submit');

  const saved = await db.users.findOne({ /* ... */ });
  expect(saved.name).toBe('山田太郎');

  // Arabic
  await page.fill('#name', 'محمد');
  // Emoji
  await page.fill('#bio', '👋🌍');

  expect(saved.bio).toBe('👋🌍');
});

Agent-Driven Localization Testing

// Comprehensive localization validation
await Task("Localization Testing", {
  url: 'https://example.com',
  locales: ['en-US', 'fr-FR', 'de-DE', 'ja-JP', 'ar-SA'],
  checks: ['translations', 'formats', 'rtl', 'unicode'],
  detectHardcodedStrings: true
}, "qe-test-generator");

// Returns:
// {
//   locales: 5,
//   missingTranslations: 3,
//   formatIssues: 1,
//   rtlIssues: 0,
//   hardcodedStrings: ['button.submit', 'header.title']
// }

Agent Coordination Hints

Memory Namespace

aqe/localization-testing/
├── translations/*       - Translation coverage
├── formats/*            - Locale-specific formats
├── rtl-validation/*     - RTL layout checks
└── unicode/*            - Character encoding tests

Fleet Coordination

const l10nFleet = await FleetManager.coordinate({
  strategy: 'localization-testing',
  agents: [
    'qe-test-generator',   // Generate l10n tests
    'qe-test-executor',    // Execute across locales
    'qe-visual-tester'     // RTL visual validation
  ],
  topology: 'parallel'
});

Related Skills

• accessibility-testing - Language accessibility
• compatibility-testing - Cross-platform i18n
• visual-testing-advanced - RTL visual regression

Remember

With Agents: Agents validate translation coverage, detect hardcoded strings, test locale-specific formatting, and verify RTL layouts automatically across all supported languages.