Updated the test system

test/deepClone.test.js

@@ -0,0 +1,22 @@
+const expect = require('expect');
+const {deepClone} = require('./_30s.js');
+
+test('deepClone is a Function', () => {
+  expect(deepClone).toBeInstanceOf(Function);
+});
+const a = { foo: 'bar', obj: { a: 1, b: 2 } };
+const b = deepClone(a);
+const c = [{ foo: 'bar' }];
+const d = deepClone(c);
+test('Shallow cloning works', () => {
+  expect(a).not.toBe(b);
+});
+test('Deep cloning works', () => {
+  expect(a.obj).not.toBe(b.obj);
+});
+test('Array shallow cloning works', () => {
+  expect(c).not.toBe(d);
+});
+test('Array deep cloning works', () => {
+  expect(c[0]).not.toBe(d[0]);
+});