const {squareSum} = require('./_30s.js'); test('squareSum is a Function', () => { expect(squareSum).toBeInstanceOf(Function); }); test('squareSum returns the proper result', () => { expect(squareSum(2, 3, 4)).toBe(29); }); test('works with negative numbers', () => { expect(squareSum(-2, 3, -4)).toBe(29); }); test('NaN when parameters have text', () => { expect(squareSum(-2, 3, -4, 'text')).toBe(NaN); });