Updated the test system

test/get.test.js

@@ -0,0 +1,10 @@
+const expect = require('expect');
+const {get} = require('./_30s.js');
+
+test('get is a Function', () => {
+  expect(get).toBeInstanceOf(Function);
+});
+const obj = { selector: { to: { val: 'val to get' } } };
+test('Retrieve a property indicated by the selector from an object.', () => {
+  expect(get(obj, 'selector.to.val')).toEqual(['val to get']);
+});