Created ScrollToTop test

src/common/ScrollToTop.js

@@ -7,10 +7,10 @@ const ScrollToTop = ({ scrollTo }) => class ScrollToTop extends React.Component
     children: PropTypes.node,
   };
 
-  componentDidUpdate(prevProps) {
+  componentDidUpdate({ location: prevLocation }) {
     const { location } = this.props;
 
-    if (location !== prevProps.location) {
+    if (location !== prevLocation) {
       scrollTo(0, 0);
     }
   }

test/common/ScrollToTop.test.js

@@ -0,0 +1,29 @@
+import React from 'react';
+import { shallow } from 'enzyme';
+import * as sinon from 'sinon';
+import createScrollToTop from '../../src/common/ScrollToTop';
+
+describe('<ScrollToTop />', () => {
+  let wrapper;
+  const window = {
+    scrollTo: sinon.spy(),
+  };
+
+  beforeEach(() => {
+    const ScrollToTop = createScrollToTop(window);
+
+    wrapper = shallow(<ScrollToTop locaction={{ href: 'foo' }}>Foobar</ScrollToTop>);
+  });
+
+  afterEach(() => {
+    wrapper.unmount();
+    window.scrollTo.resetHistory();
+  });
+
+  it('just renders children', () => expect(wrapper.text()).toEqual('Foobar'));
+
+  it('scrolls to top when location changes', () => {
+    wrapper.instance().componentDidUpdate({ location: { href: 'bar' } });
+    expect(window.scrollTo.calledOnce).toEqual(true);
+  });
+});