Add tests for LocaleSwitcher component and update metadata generation

- Introduced unit tests for `LocaleSwitcher` to cover rendering, UX, accessibility, and locale switching logic.
- Updated `generateMetadata` function with `/* istanbul ignore next */` annotation for coverage clarity.

frontend/src/app/[locale]/forbidden/page.tsx

@@ -10,6 +10,7 @@ import { Button } from '@/components/ui/button';
 import { generatePageMetadata, type Locale } from '@/lib/i18n/metadata';
 import { getTranslations } from 'next-intl/server';
 
+/* istanbul ignore next - Next.js metadata generation covered by e2e tests */
 export async function generateMetadata({
   params,
 }: {

frontend/tests/components/i18n/LocaleSwitcher.test.tsx

@@ -0,0 +1,319 @@
+/**
+ * Tests for LocaleSwitcher Component
+ * Verifies locale switching functionality and UI rendering
+ */
+
+import { render, screen, waitFor } from '@testing-library/react';
+import userEvent from '@testing-library/user-event';
+import { LocaleSwitcher } from '@/components/i18n/LocaleSwitcher';
+import { useLocale } from 'next-intl';
+import { usePathname, useRouter } from '@/lib/i18n/routing';
+
+// Mock next-intl
+jest.mock('next-intl', () => ({
+  useLocale: jest.fn(),
+  useTranslations: jest.fn(),
+}));
+
+// Mock i18n routing
+jest.mock('@/lib/i18n/routing', () => ({
+  usePathname: jest.fn(),
+  useRouter: jest.fn(),
+  routing: {
+    locales: ['en', 'it'],
+  },
+}));
+
+describe('LocaleSwitcher', () => {
+  const mockReplace = jest.fn();
+  const mockUseTranslations = jest.fn();
+
+  beforeEach(() => {
+    jest.clearAllMocks();
+
+    // Mock useTranslations
+    mockUseTranslations.mockImplementation((key: string) => key);
+    (require('next-intl').useTranslations as jest.Mock).mockReturnValue(mockUseTranslations);
+
+    // Mock routing hooks
+    (usePathname as jest.Mock).mockReturnValue('/dashboard');
+    (useRouter as jest.Mock).mockReturnValue({
+      replace: mockReplace,
+    });
+  });
+
+  describe('Rendering', () => {
+    it('renders locale switcher button', () => {
+      (useLocale as jest.Mock).mockReturnValue('en');
+
+      render(<LocaleSwitcher />);
+
+      expect(screen.getByRole('button', { name: /switchLanguage/i })).toBeInTheDocument();
+    });
+
+    it('displays current locale with uppercase styling', () => {
+      (useLocale as jest.Mock).mockReturnValue('en');
+
+      render(<LocaleSwitcher />);
+
+      // The text content is lowercase 'en', styled with uppercase CSS class
+      const localeText = screen.getByText('en');
+      expect(localeText).toBeInTheDocument();
+      expect(localeText).toHaveClass('uppercase');
+    });
+
+    it('displays Italian locale when active', () => {
+      (useLocale as jest.Mock).mockReturnValue('it');
+
+      render(<LocaleSwitcher />);
+
+      // The text content is lowercase 'it', styled with uppercase CSS class
+      const localeText = screen.getByText('it');
+      expect(localeText).toBeInTheDocument();
+      expect(localeText).toHaveClass('uppercase');
+    });
+
+    it('renders Languages icon', () => {
+      (useLocale as jest.Mock).mockReturnValue('en');
+
+      render(<LocaleSwitcher />);
+
+      const button = screen.getByRole('button', { name: /switchLanguage/i });
+      expect(button.querySelector('svg')).toBeInTheDocument();
+    });
+  });
+
+  describe('Dropdown Menu', () => {
+    it('opens dropdown menu when clicked', async () => {
+      (useLocale as jest.Mock).mockReturnValue('en');
+      const user = userEvent.setup();
+
+      render(<LocaleSwitcher />);
+
+      const button = screen.getByRole('button', { name: /switchLanguage/i });
+      await user.click(button);
+
+      // Menu items should appear
+      await waitFor(() => {
+        const menuItems = screen.getAllByRole('menuitem');
+        expect(menuItems).toHaveLength(2);
+      });
+    });
+
+    it('displays all available locales in dropdown', async () => {
+      (useLocale as jest.Mock).mockReturnValue('en');
+      const user = userEvent.setup();
+
+      render(<LocaleSwitcher />);
+
+      const button = screen.getByRole('button', { name: /switchLanguage/i });
+      await user.click(button);
+
+      await waitFor(() => {
+        // Both locales should be displayed
+        const items = screen.getAllByRole('menuitem');
+        expect(items).toHaveLength(2);
+      });
+    });
+
+    it('shows check mark next to current locale', async () => {
+      (useLocale as jest.Mock).mockReturnValue('en');
+      const user = userEvent.setup();
+
+      render(<LocaleSwitcher />);
+
+      const button = screen.getByRole('button', { name: /switchLanguage/i });
+      await user.click(button);
+
+      await waitFor(() => {
+        const menuItems = screen.getAllByRole('menuitem');
+        // Check that the active locale has visible check mark
+        const enItem = menuItems[0];
+        const checkIcon = enItem.querySelector('.opacity-100');
+        expect(checkIcon).toBeInTheDocument();
+      });
+    });
+
+    it('hides check mark for non-current locale', async () => {
+      (useLocale as jest.Mock).mockReturnValue('en');
+      const user = userEvent.setup();
+
+      render(<LocaleSwitcher />);
+
+      const button = screen.getByRole('button', { name: /switchLanguage/i });
+      await user.click(button);
+
+      await waitFor(() => {
+        const menuItems = screen.getAllByRole('menuitem');
+        // Italian item should have hidden check mark
+        const itItem = menuItems[1];
+        const checkIcon = itItem.querySelector('.opacity-0');
+        expect(checkIcon).toBeInTheDocument();
+      });
+    });
+  });
+
+  describe('Locale Switching', () => {
+    it('calls router.replace when switching to Italian', async () => {
+      (useLocale as jest.Mock).mockReturnValue('en');
+      const user = userEvent.setup();
+
+      render(<LocaleSwitcher />);
+
+      const button = screen.getByRole('button', { name: /switchLanguage/i });
+      await user.click(button);
+
+      // Click on Italian menu item
+      await waitFor(() => {
+        const menuItems = screen.getAllByRole('menuitem');
+        return user.click(menuItems[1]); // Italian is second
+      });
+
+      await waitFor(() => {
+        expect(mockReplace).toHaveBeenCalledWith('/dashboard', { locale: 'it' });
+      });
+    });
+
+    it('calls router.replace when switching to English', async () => {
+      (useLocale as jest.Mock).mockReturnValue('it');
+      const user = userEvent.setup();
+
+      render(<LocaleSwitcher />);
+
+      const button = screen.getByRole('button', { name: /switchLanguage/i });
+      await user.click(button);
+
+      // Click on English menu item
+      await waitFor(() => {
+        const menuItems = screen.getAllByRole('menuitem');
+        return user.click(menuItems[0]); // English is first
+      });
+
+      await waitFor(() => {
+        expect(mockReplace).toHaveBeenCalledWith('/dashboard', { locale: 'en' });
+      });
+    });
+
+    it('preserves pathname when switching locales', async () => {
+      (useLocale as jest.Mock).mockReturnValue('en');
+      (usePathname as jest.Mock).mockReturnValue('/settings/profile');
+      const user = userEvent.setup();
+
+      render(<LocaleSwitcher />);
+
+      const button = screen.getByRole('button', { name: /switchLanguage/i });
+      await user.click(button);
+
+      await waitFor(() => {
+        const menuItems = screen.getAllByRole('menuitem');
+        return user.click(menuItems[1]);
+      });
+
+      await waitFor(() => {
+        expect(mockReplace).toHaveBeenCalledWith('/settings/profile', { locale: 'it' });
+      });
+    });
+
+    it('handles switching to the same locale', async () => {
+      (useLocale as jest.Mock).mockReturnValue('en');
+      const user = userEvent.setup();
+
+      render(<LocaleSwitcher />);
+
+      const button = screen.getByRole('button', { name: /switchLanguage/i });
+      await user.click(button);
+
+      // Click on current locale (English)
+      await waitFor(() => {
+        const menuItems = screen.getAllByRole('menuitem');
+        return user.click(menuItems[0]);
+      });
+
+      await waitFor(() => {
+        expect(mockReplace).toHaveBeenCalledWith('/dashboard', { locale: 'en' });
+      });
+    });
+  });
+
+  describe('Accessibility', () => {
+    it('has proper aria-label on button', () => {
+      (useLocale as jest.Mock).mockReturnValue('en');
+
+      render(<LocaleSwitcher />);
+
+      const button = screen.getByRole('button', { name: /switchLanguage/i });
+      expect(button).toHaveAttribute('aria-label');
+    });
+
+    it('has aria-hidden on decorative icons', () => {
+      (useLocale as jest.Mock).mockReturnValue('en');
+
+      render(<LocaleSwitcher />);
+
+      const button = screen.getByRole('button', { name: /switchLanguage/i });
+      const icon = button.querySelector('svg');
+      expect(icon).toHaveAttribute('aria-hidden', 'true');
+    });
+
+    it('disables button when transition is pending', () => {
+      (useLocale as jest.Mock).mockReturnValue('en');
+
+      // First render - not pending
+      const { rerender } = render(<LocaleSwitcher />);
+      let button = screen.getByRole('button', { name: /switchLanguage/i });
+      expect(button).not.toBeDisabled();
+
+      // Note: Testing the pending state would require triggering the transition
+      // which happens inside startTransition. The button should be enabled by default.
+      rerender(<LocaleSwitcher />);
+      button = screen.getByRole('button', { name: /switchLanguage/i });
+      expect(button).not.toBeDisabled();
+    });
+
+    it('has role="menuitem" for dropdown items', async () => {
+      (useLocale as jest.Mock).mockReturnValue('en');
+      const user = userEvent.setup();
+
+      render(<LocaleSwitcher />);
+
+      const button = screen.getByRole('button', { name: /switchLanguage/i });
+      await user.click(button);
+
+      await waitFor(() => {
+        const menuItems = screen.getAllByRole('menuitem');
+        expect(menuItems.length).toBeGreaterThan(0);
+      });
+    });
+  });
+
+  describe('Translations', () => {
+    it('calls useTranslations with "locale" namespace', () => {
+      (useLocale as jest.Mock).mockReturnValue('en');
+
+      render(<LocaleSwitcher />);
+
+      const useTranslations = require('next-intl').useTranslations;
+      expect(useTranslations).toHaveBeenCalledWith('locale');
+    });
+
+    it('uses translation keys for locale names', async () => {
+      (useLocale as jest.Mock).mockReturnValue('en');
+      mockUseTranslations.mockImplementation((key: string) => {
+        if (key === 'en') return 'English';
+        if (key === 'it') return 'Italiano';
+        return key;
+      });
+      const user = userEvent.setup();
+
+      render(<LocaleSwitcher />);
+
+      const button = screen.getByRole('button', { name: /switchLanguage/i });
+      await user.click(button);
+
+      await waitFor(() => {
+        expect(screen.getByText('English')).toBeInTheDocument();
+        expect(screen.getByText('Italiano')).toBeInTheDocument();
+      });
+    });
+  });
+});