Updated the test system

test/renameKeys.test.js

@@ -0,0 +1,11 @@
+const expect = require('expect');
+const {renameKeys} = require('./_30s.js');
+
+test('renameKeys is a Function', () => {
+  expect(renameKeys).toBeInstanceOf(Function);
+});
+const obj = { name: 'Bobo', job: 'Front-End Master', shoeSize: 100 };
+const renamedObj = renameKeys({ name: 'firstName', job: 'passion' }, obj);
+test('renameKeys is a Function', () => {
+  expect(renamedObj).toEqual({ firstName: 'Bobo', passion: 'Front-End Master', shoeSize: 100 });
+});