Test/tests/index.test.js

const { add, greet } = require('../src/index');

describe('Utility functions', () => {
  test('add should sum two numbers', () => {
    expect(add(2, 3)).toBe(5);
    expect(add(-1, 1)).toBe(0);
  });

  test('greet should return a greeting', () => {
    expect(greet('World')).toBe('Hello, World!');
    expect(greet('Marius')).toBe('Hello, Marius!');
  });
});