import expect from 'expect'; import timer from '../timer-utils'; describe('timer', () => { it('records how long a function takes to execute', () => { const add100k = (number) => { for (let i = 0; i < 100000; i += 1) { number += 1; } return number; }; const timedFn = timer(add100k); const result = timedFn(70); expect(result).toEqual(100070); expect(timedFn.time).toBeA('number'); }); });