open-design/apps/web/tests/i18n/locales.test.ts

import { describe, expect, it } from 'vitest';
import { en } from '../../src/i18n/locales/en';
import { LOCALES, LOCALE_LABEL, type Dict, type Locale } from '../../src/i18n/types';

const EXPECTED_LOCALES = ['en', 'de', 'zh-CN', 'zh-TW', 'pt-BR', 'es-ES', 'ru', 'fa', 'ar', 'ja', 'ko', 'pl', 'hu', 'fr', 'uk', 'tr'];

function placeholders(value: string): string[] {
  const names: string[] = [];
  for (const match of value.matchAll(/\{(\w+)\}/g)) {
    if (match[1]) {
      names.push(match[1]);
    }
  }
  return names.sort();
}

async function loadDict(locale: Locale): Promise<Dict> {
  const module = await import(`../../src/i18n/locales/${locale}.ts`);
  const dict = Object.values(module).find((value): value is Dict => {
    return Boolean(value) && typeof value === 'object';
  });
  if (!dict) {
    throw new Error(`No dictionary export found for locale ${locale}`);
  }
  return dict;
}

describe('i18n locales', () => {
  it('registers every supported locale in the language menu', () => {
    expect(LOCALES).toEqual(EXPECTED_LOCALES);
    expect((LOCALE_LABEL as Record<string, string>).de).toBe('Deutsch');
    expect((LOCALE_LABEL as Record<string, string>).ja).toBe('日本語');
  });

  it('keeps locale dictionaries aligned with English keys and placeholders', async () => {
    const englishKeys = Object.keys(en).sort();

    for (const locale of LOCALES) {
      const dict = await loadDict(locale);
      expect(Object.keys(dict).sort()).toEqual(englishKeys);

      for (const key of englishKeys) {
        const dictKey = key as keyof Dict;
        expect(placeholders(dict[dictKey]), `${locale}.${key}`).toEqual(
          placeholders(en[dictKey]),
        );
      }
    }
  });
});