Have you written tests? Which ones specifically?

Yes, I have written tests for frontend applications. Mainly used:

• Unit tests with Jest to test individual functions and components.
• Integration tests with React Testing Library to test component interactions.

Example of a simple unit test with Jest:

import { sum } from './utils';

test('adds 1 + 2 to equal 3', () => {
  expect(sum(1, 2)).toBe(3);
});

Tests help maintain code quality and quickly identify errors when making changes.