feat: add tests for page in App Router

src/app/[locale]/about/page.test.tsx

@@ -0,0 +1,18 @@
+import { render, screen } from '@testing-library/react';
+
+import About from './page';
+
+// The easiest solution to mock `next/router`: https://github.com/vercel/next.js/issues/7479
+// The mock has been moved to `__mocks__` folder to avoid duplication
+
+describe('About page', () => {
+  describe('Render method', () => {
+    it('should have two paragraphs of `Lorem ipsum`', () => {
+      render(<About />);
+
+      const paragraph = screen.getAllByText(/Lorem ipsum/);
+
+      expect(paragraph).toHaveLength(2);
+    });
+  });
+});

src/app/[locale]/page.test.tsx

@@ -0,0 +1,20 @@
+import { render, screen } from '@testing-library/react';
+
+import Index from './page';
+
+// The easiest solution to mock `next/router`: https://github.com/vercel/next.js/issues/7479
+// The mock has been moved to `__mocks__` folder to avoid duplication
+
+describe('Index page', () => {
+  describe('Render method', () => {
+    it('should have h1 tag', () => {
+      render(<Index />);
+
+      const heading = screen.getByRole('heading', {
+        name: /Boilerplate code/,
+      });
+
+      expect(heading).toBeInTheDocument();
+    });
+  });
+});