const expect = require('expect'); const pickBy = require('./pickBy.js'); test('pickBy is a Function', () => { expect(pickBy).toBeInstanceOf(Function); }); test('Creates an object composed of the properties the given function returns truthy for.', () => { expect(pickBy({ a: 1, b: '2', c: 3 }, x => typeof x === 'number')).toEqual({ 'a': 1, 'c': 3 }); });