and index.jsx tests

__tests__/index.test.jsx

@@ -0,0 +1,22 @@
+import React from 'react';
+import ReactDOM from 'react-dom';
+
+import api from '../src/api';
+
+import indexToRender from '../src/index';
+
+const custom_logo = (<div>logo</div>);
+const custom_login_info = 'custom login info';
+
+jest.mock('react-dom', () => ({ render: jest.fn() }));
+
+describe('index.jsx', () => {
+  test('renders without crashing', async () => {
+    api.getRoot = jest.fn().mockImplementation(() => Promise
+      .resolve({ data: { custom_logo, custom_login_info } }));
+
+    await indexToRender();
+
+    expect(ReactDOM.render).toHaveBeenCalled();
+  });
+});

src/index.jsx

@@ -11,9 +11,15 @@ import './app.scss';
 
 const el = document.getElementById('app');
 
-api.getRoot()
-  .then(({ data }) => {
-    const { custom_logo, custom_login_info } = data;
+const main = () => {
+  api.getRoot()
+    .then(({ data }) => {
+      const { custom_logo, custom_login_info } = data;
 
-    render(<App logo={custom_logo} loginInfo={custom_login_info} />, el);
-  });
+      render(<App logo={custom_logo} loginInfo={custom_login_info} />, el);
+    });
+};
+
+main();
+
+export default main;