More unit tests

src/app/App.js

@@ -10,12 +10,15 @@ import './App.css';
 
 const store = configureStore();
 
-ReactDOM.render(
+const App = () => (
   <Provider store={store}>
     <MainWindow />
-  </Provider>,
-  document.getElementById('root'),
+  </Provider>
 );
 
+ReactDOM.render(<App />, document.getElementById('root') || document.createElement('div'));
+
 KeyboardShourtcutsService.initializeDefaults(store);
 WatcherService.initialize(store);
+
+export default App;

src/tests/Components/App.spec.js

@@ -0,0 +1,15 @@
+import React from 'react';
+import { expect } from 'chai';
+import Enzyme, { shallow } from 'enzyme';
+import Adapter from 'enzyme-adapter-react-16';
+
+import App from '../../app/App';
+
+Enzyme.configure({ adapter: new Adapter() });
+
+describe('App component tests', () => {
+  it('should render', () => {
+    const wrapper = shallow(<App />);
+    expect(wrapper).to.have.length(1);
+  });
+});