Updated the test system

test/shallowClone.test.js

@@ -0,0 +1,14 @@
+const expect = require('expect');
+const {shallowClone} = require('./_30s.js');
+
+test('shallowClone is a Function', () => {
+  expect(shallowClone).toBeInstanceOf(Function);
+});
+const a = { foo: 'bar', obj: { a: 1, b: 2 } };
+const b = shallowClone(a);
+test('Shallow cloning works', () => {
+  expect(a).not.toBe(b);
+});
+test('Does not clone deeply', () => {
+  expect(a.obj).toBe(b.obj);
+});