Updated the test system

test/reject.test.js

@@ -0,0 +1,14 @@
+const expect = require('expect');
+const {reject} = require('./_30s.js');
+
+test('reject is a Function', () => {
+  expect(reject).toBeInstanceOf(Function);
+});
+const noEvens = reject(x => x % 2 === 0, [1, 2, 3, 4, 5]);
+test('Works with numbers', () => {
+  expect(noEvens).toEqual([1, 3, 5]);
+});
+const fourLettersOrLess = reject(word => word.length > 4, ['Apple', 'Pear', 'Kiwi', 'Banana']);
+test('Works with strings', () => {
+  expect(fourLettersOrLess).toEqual(['Pear', 'Kiwi']);
+});