const expect = require('expect'); const symmetricDifference = require('./symmetricDifference.js'); test('symmetricDifference is a Function', () => { expect(symmetricDifference).toBeInstanceOf(Function); }); test('Returns the symmetric difference between two arrays.', () => { expect(symmetricDifference([1, 2, 3], [1, 2, 4])).toEqual([3, 4]); });