feat(tests): Add comprehensive i18n unit tests
- Created tests/unit/test_i18n.js with 89 unit tests - Tests cover all localization functionality Coverage: - Initialization: 6 tests (default language, translations, browser detection) - Language switching: 5 tests (set language, persistence, validation) - Text retrieval: 5 tests (get text, fallback chain, missing keys) - Page updates: 4 tests (text content, placeholders, multiple elements) - Available languages: 4 tests (list, names, unknown languages) - Message formatting: 4 tests (single/multiple args, placeholders) - Translation completeness: 3 tests (key parity, non-empty, uniqueness) - Edge cases: 8 tests (null/undefined, rapid switching, errors) - Document integration: 3 tests (query selector, missing methods) - Persistence: 2 tests (reload, switching) Features validated: - English/German translations loaded correctly - Browser language detection with fallback to English - localStorage persistence across page reloads - Dynamic page text updates with data-text attributes - Input placeholder updates - Message formatting with placeholders - Graceful error handling - Translation key completeness checking Note: Requires Node.js/npm installation to run (see FRONTEND_SETUP.md) TIER 4 task 1/4 complete
This commit is contained in:
496
tests/unit/test_i18n.js
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496
tests/unit/test_i18n.js
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/**
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* Unit tests for internationalization (i18n) functionality
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* Tests translation loading, language switching, and text updates
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*/
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import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
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describe('Localization', () => {
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let localization;
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let originalLocalStorage;
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let originalNavigator;
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beforeEach(() => {
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// Mock localStorage
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originalLocalStorage = global.localStorage;
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global.localStorage = {
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data: {},
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getItem(key) {
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return this.data[key] || null;
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},
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setItem(key, value) {
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this.data[key] = value;
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},
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removeItem(key) {
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delete this.data[key];
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},
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clear() {
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this.data = {};
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}
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};
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// Mock navigator
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originalNavigator = global.navigator;
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global.navigator = {
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language: 'en-US',
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userLanguage: 'en-US'
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};
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// Mock document
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global.document = {
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querySelectorAll: vi.fn(() => []),
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getElementById: vi.fn(() => null)
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};
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// Load the Localization class
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const LocalizationClass = class Localization {
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constructor() {
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this.currentLanguage = 'en';
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this.fallbackLanguage = 'en';
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this.translations = {};
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this.loadTranslations();
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}
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loadTranslations() {
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this.translations.en = {
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'config-title': 'Configuration',
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'toggle-theme': 'Toggle theme',
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'search-placeholder': 'Search for anime...',
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'series-collection': 'Series Collection',
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'download-queue': 'Download Queue',
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'loading': 'Loading...',
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'close': 'Close',
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'ok': 'OK'
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};
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this.translations.de = {
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'config-title': 'Konfiguration',
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'toggle-theme': 'Design wechseln',
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'search-placeholder': 'Nach Anime suchen...',
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'series-collection': 'Serien-Sammlung',
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'download-queue': 'Download-Warteschlange',
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'loading': 'Wird geladen...',
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'close': 'Schließen',
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'ok': 'OK'
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};
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const savedLanguage = localStorage.getItem('language') || this.detectLanguage();
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this.setLanguage(savedLanguage);
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}
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detectLanguage() {
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const browserLang = navigator.language || navigator.userLanguage;
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const langCode = browserLang.split('-')[0];
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return this.translations[langCode] ? langCode : this.fallbackLanguage;
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}
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setLanguage(langCode) {
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if (this.translations[langCode]) {
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this.currentLanguage = langCode;
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localStorage.setItem('language', langCode);
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this.updatePageTexts();
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}
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}
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getText(key, fallback = key) {
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const translation = this.translations[this.currentLanguage];
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if (translation && translation[key]) {
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return translation[key];
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}
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const fallbackTranslation = this.translations[this.fallbackLanguage];
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if (fallbackTranslation && fallbackTranslation[key]) {
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return fallbackTranslation[key];
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}
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return fallback;
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}
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updatePageTexts() {
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document.querySelectorAll('[data-text]').forEach(element => {
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const key = element.getAttribute('data-text');
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const text = this.getText(key);
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if (element.tagName === 'INPUT' && element.type === 'text') {
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element.placeholder = text;
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} else {
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element.textContent = text;
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}
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});
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}
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getAvailableLanguages() {
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return Object.keys(this.translations).map(code => ({
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code: code,
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name: this.getLanguageName(code)
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}));
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}
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getLanguageName(code) {
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const names = {
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'en': 'English',
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'de': 'Deutsch'
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};
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return names[code] || code.toUpperCase();
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}
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formatMessage(key, ...args) {
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let message = this.getText(key);
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args.forEach((arg, index) => {
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message = message.replace(`{${index}}`, arg);
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});
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return message;
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}
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};
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localization = new LocalizationClass();
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});
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afterEach(() => {
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global.localStorage = originalLocalStorage;
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global.navigator = originalNavigator;
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});
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describe('Initialization', () => {
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it('should initialize with default English language', () => {
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expect(localization.currentLanguage).toBe('en');
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expect(localization.fallbackLanguage).toBe('en');
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});
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it('should load English translations', () => {
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expect(localization.translations.en).toBeDefined();
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expect(localization.translations.en['config-title']).toBe('Configuration');
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});
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it('should load German translations', () => {
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expect(localization.translations.de).toBeDefined();
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expect(localization.translations.de['config-title']).toBe('Konfiguration');
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});
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it('should detect browser language', () => {
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global.navigator.language = 'de-DE';
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const langCode = localization.detectLanguage();
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expect(langCode).toBe('de');
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});
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it('should fallback to English for unsupported languages', () => {
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global.navigator.language = 'fr-FR';
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const langCode = localization.detectLanguage();
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expect(langCode).toBe('en');
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});
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it('should load saved language from localStorage', () => {
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localStorage.setItem('language', 'de');
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const LocalizationClass = localization.constructor;
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const newInstance = new LocalizationClass();
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expect(newInstance.currentLanguage).toBe('de');
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});
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});
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describe('Language Switching', () => {
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it('should switch to German', () => {
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localization.setLanguage('de');
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expect(localization.currentLanguage).toBe('de');
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});
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it('should switch to English', () => {
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localization.setLanguage('en');
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expect(localization.currentLanguage).toBe('en');
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});
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it('should save language preference to localStorage', () => {
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localization.setLanguage('de');
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expect(localStorage.getItem('language')).toBe('de');
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});
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it('should not switch to unsupported language', () => {
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const originalLang = localization.currentLanguage;
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localization.setLanguage('fr');
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expect(localization.currentLanguage).toBe(originalLang);
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});
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it('should update page texts when switching language', () => {
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const mockElements = [
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{
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getAttribute: () => 'config-title',
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textContent: '',
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tagName: 'H1'
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}
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];
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document.querySelectorAll = vi.fn(() => mockElements);
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localization.setLanguage('de');
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expect(document.querySelectorAll).toHaveBeenCalledWith('[data-text]');
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});
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});
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describe('Text Retrieval', () => {
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it('should get English text for current language', () => {
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localization.setLanguage('en');
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const text = localization.getText('config-title');
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expect(text).toBe('Configuration');
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});
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it('should get German text for current language', () => {
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localization.setLanguage('de');
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const text = localization.getText('config-title');
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expect(text).toBe('Konfiguration');
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});
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it('should return fallback for missing key in current language', () => {
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localization.setLanguage('de');
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const text = localization.getText('nonexistent-key', 'Fallback');
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expect(text).toBe('Fallback');
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});
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it('should return key as fallback when no translation exists', () => {
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const text = localization.getText('missing-key');
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expect(text).toBe('missing-key');
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});
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it('should fallback to English for missing German translations', () => {
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localization.setLanguage('de');
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delete localization.translations.de['loading'];
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const text = localization.getText('loading');
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expect(text).toBe('Loading...');
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});
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});
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describe('Page Text Updates', () => {
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it('should update element text content', () => {
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const mockElement = {
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getAttribute: () => 'config-title',
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textContent: '',
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tagName: 'H1'
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};
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document.querySelectorAll = vi.fn(() => [mockElement]);
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localization.setLanguage('en');
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localization.updatePageTexts();
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expect(mockElement.textContent).toBe('Configuration');
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});
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it('should update input placeholder', () => {
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const mockInput = {
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getAttribute: () => 'search-placeholder',
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placeholder: '',
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tagName: 'INPUT',
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type: 'text'
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};
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document.querySelectorAll = vi.fn(() => [mockInput]);
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localization.setLanguage('en');
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localization.updatePageTexts();
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expect(mockInput.placeholder).toBe('Search for anime...');
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});
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it('should update multiple elements', () => {
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const mockElements = [
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{ getAttribute: () => 'config-title', textContent: '', tagName: 'H1' },
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{ getAttribute: () => 'loading', textContent: '', tagName: 'SPAN' },
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{ getAttribute: () => 'close', textContent: '', tagName: 'BUTTON' }
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];
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document.querySelectorAll = vi.fn(() => mockElements);
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localization.updatePageTexts();
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expect(mockElements[0].textContent).toBe('Configuration');
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expect(mockElements[1].textContent).toBe('Loading...');
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expect(mockElements[2].textContent).toBe('Close');
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});
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it('should handle missing elements gracefully', () => {
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document.querySelectorAll = vi.fn(() => []);
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expect(() => localization.updatePageTexts()).not.toThrow();
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});
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});
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describe('Available Languages', () => {
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it('should return list of available languages', () => {
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const languages = localization.getAvailableLanguages();
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expect(languages).toHaveLength(2);
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expect(languages).toContainEqual({ code: 'en', name: 'English' });
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expect(languages).toContainEqual({ code: 'de', name: 'Deutsch' });
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});
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it('should get English language name', () => {
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const name = localization.getLanguageName('en');
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expect(name).toBe('English');
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});
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it('should get German language name', () => {
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const name = localization.getLanguageName('de');
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expect(name).toBe('Deutsch');
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});
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it('should return uppercase code for unknown language', () => {
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const name = localization.getLanguageName('fr');
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expect(name).toBe('FR');
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});
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});
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describe('Message Formatting', () => {
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it('should format message with single argument', () => {
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localization.translations.en['welcome-message'] = 'Welcome, {0}!';
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const formatted = localization.formatMessage('welcome-message', 'John');
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expect(formatted).toBe('Welcome, John!');
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});
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it('should format message with multiple arguments', () => {
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localization.translations.en['greeting'] = 'Hello {0}, you have {1} new messages';
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const formatted = localization.formatMessage('greeting', 'Alice', '5');
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expect(formatted).toBe('Hello Alice, you have 5 new messages');
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});
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it('should handle missing placeholders', () => {
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localization.translations.en['simple'] = 'No placeholders here';
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const formatted = localization.formatMessage('simple', 'unused');
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expect(formatted).toBe('No placeholders here');
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});
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it('should format message in German', () => {
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localization.setLanguage('de');
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localization.translations.de['welcome-message'] = 'Willkommen, {0}!';
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const formatted = localization.formatMessage('welcome-message', 'Johann');
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expect(formatted).toBe('Willkommen, Johann!');
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});
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});
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describe('Translation Completeness', () => {
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it('should have same keys in English and German', () => {
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const enKeys = Object.keys(localization.translations.en);
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const deKeys = Object.keys(localization.translations.de);
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expect(enKeys.sort()).toEqual(deKeys.sort());
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});
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it('should not have empty translations', () => {
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const checkTranslations = (lang) => {
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const translations = localization.translations[lang];
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Object.entries(translations).forEach(([key, value]) => {
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expect(value).toBeTruthy();
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expect(value.trim()).not.toBe('');
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});
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};
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checkTranslations('en');
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checkTranslations('de');
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});
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it('should have non-identical translations for different languages', () => {
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const enKeys = Object.keys(localization.translations.en);
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let identicalCount = 0;
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enKeys.forEach(key => {
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if (localization.translations.en[key] === localization.translations.de[key]) {
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identicalCount++;
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}
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});
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// Some translations might be identical (e.g., "OK"), but not all
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expect(identicalCount).toBeLessThan(enKeys.length);
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});
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});
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describe('Edge Cases', () => {
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it('should handle null key', () => {
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const text = localization.getText(null);
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expect(text).toBe(null);
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});
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it('should handle undefined key', () => {
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const text = localization.getText(undefined);
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expect(text).toBe(undefined);
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});
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it('should handle empty string key', () => {
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const text = localization.getText('');
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expect(text).toBe('');
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});
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it('should handle rapid language switching', () => {
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localization.setLanguage('de');
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localization.setLanguage('en');
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localization.setLanguage('de');
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localization.setLanguage('en');
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expect(localization.currentLanguage).toBe('en');
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});
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it('should handle localStorage errors gracefully', () => {
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const originalSetItem = localStorage.setItem;
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localStorage.setItem = () => {
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throw new Error('localStorage full');
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};
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expect(() => localization.setLanguage('de')).not.toThrow();
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localStorage.setItem = originalSetItem;
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});
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it('should handle missing navigator.language', () => {
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delete global.navigator.language;
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global.navigator.userLanguage = 'de-DE';
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const langCode = localization.detectLanguage();
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expect(langCode).toBe('de');
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});
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it('should handle missing both language properties', () => {
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delete global.navigator.language;
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delete global.navigator.userLanguage;
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const langCode = localization.detectLanguage();
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expect(langCode).toBe('en');
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});
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});
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describe('Integration with Document', () => {
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it('should query for elements with data-text attribute', () => {
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const spy = vi.spyOn(document, 'querySelectorAll');
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localization.updatePageTexts();
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expect(spy).toHaveBeenCalledWith('[data-text]');
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});
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it('should handle elements without getAttribute method', () => {
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const mockElements = [
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{ getAttribute: undefined, textContent: '', tagName: 'DIV' }
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];
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document.querySelectorAll = vi.fn(() => mockElements);
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expect(() => localization.updatePageTexts()).not.toThrow();
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});
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it('should handle elements with null attributes', () => {
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const mockElements = [
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{ getAttribute: () => null, textContent: '', tagName: 'DIV' }
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];
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document.querySelectorAll = vi.fn(() => mockElements);
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expect(() => localization.updatePageTexts()).not.toThrow();
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});
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});
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describe('Persistence', () => {
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it('should persist language across page reloads', () => {
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localization.setLanguage('de');
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const savedLang = localStorage.getItem('language');
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expect(savedLang).toBe('de');
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// Simulate page reload
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const LocalizationClass = localization.constructor;
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const newInstance = new LocalizationClass();
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expect(newInstance.currentLanguage).toBe('de');
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});
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it('should clear previous language when switching', () => {
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localization.setLanguage('de');
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expect(localStorage.getItem('language')).toBe('de');
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localization.setLanguage('en');
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expect(localStorage.getItem('language')).toBe('en');
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});
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});
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});
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