Jest

function add(a, b) {
    return a + b;
}

function subtract(a, b) {
    return a - b;
}
describe('Math functions', () => {
    test('add: 2 + 3 should equal 5', () => {
        expect(add(2, 3)).toBe(5);
    });

    test('subtract: 5 - 3 should equal 2', () => {
        expect(subtract(5, 3)).toBe(2);
    });
});