add about page tests

__tests__/components/About.test.jsx

@@ -0,0 +1,15 @@
+import React from 'react';
+import { mount } from 'enzyme';
+import About from '../../src/components/About';
+
+let aboutWrapper;
+let headerElem;
+
+describe('<About />', () => {
+  test('initially renders without crashing', () => {
+    aboutWrapper = mount(<About />);
+    headerElem = aboutWrapper.find('h2');
+    expect(aboutWrapper.length).toBe(1);
+    expect(headerElem.length).toBe(1);
+  });
+});