const expect = require('expect'); const unionBy = require('./unionBy.js'); test('Testing unionBy', () => { //For more information on all the methods supported by tape //Please go to https://github.com/substack/tape expect(typeof unionBy === 'function').toBeTruthy(); expect(unionBy([2.1], [1.2, 2.3], Math.floor)).toEqual([2.1, 1.2]); });