Updated the test system

test/zip.test.js

@@ -0,0 +1,34 @@
+const expect = require('expect');
+const {zip} = require('./_30s.js');
+
+test('zip is a Function', () => {
+  expect(zip).toBeInstanceOf(Function);
+});
+test('zip([a, b], [1, 2], [true, false]) returns [[a, 1, true], [b, 2, false]]', () => {
+  expect(zip(['a', 'b'], [1, 2], [true, false])).toEqual([['a', 1, true], ['b', 2, false]]);
+});
+test('zip([a], [1, 2], [true, false]) returns [[a, 1, true], [undefined, 2, false]]', () => {
+  expect(zip(['a'], [1, 2], [true, false])).toEqual([['a', 1, true], [undefined, 2, false]]);
+});
+test('zip([]) returns []', () => {
+  expect(zip()).toEqual([]);
+});
+test('zip(123) returns []', () => {
+  expect(zip(123)).toEqual([]);
+});
+test('zip([a, b], [1, 2], [true, false]) returns an Array', () => {
+  expect(Array.isArray(zip(['a', 'b'], [1, 2], [true, false]))).toBeTruthy();
+});
+test('zip([a], [1, 2], [true, false]) returns an Array', () => {
+  expect(Array.isArray(zip(['a'], [1, 2], [true, false]))).toBeTruthy();
+});
+test('zip(null) throws an error', () => {
+  expect(() => {
+    zip(null);
+  }).toThrow();
+});
+test('zip(undefined) throws an error', () => {
+  expect(() => {
+    zip(undefined);
+  }).toThrow();
+});