const {ary} = require('./_30s.js'); test('ary is a Function', () => { expect(ary).toBeInstanceOf(Function); }); const firstTwoMax = ary(Math.max, 2); test('Discards arguments with index >=n', () => { expect([[2, 6, 'a'], [6, 4, 8], [10]].map(x => firstTwoMax(...x))).toEqual([6, 6, 10]); });