Updated the test system

test/ary.test.js

@@ -0,0 +1,10 @@
+const expect = require('expect');
+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'], [8, 4, 6], [10]].map(x => firstTwoMax(...x))).toEqual([6, 8, 10]);
+});