title: Jest mock an object
body: <p>I need to mock an object, <code>config.js</code>, rather than mocking a function as normal.  I have - </p>
  
  <pre><code>//config.js . 
  export default {
     foo: 'bar'
  }
  </code></pre>
  
  <p>I have tried - </p>
  
  <pre><code>import config from './config';
  jest.mock('./config');
  config.mockReturnValue({
     foo: 'zed'
  })
  </code></pre>
  
  <p>also - </p>
  
  <pre><code>import config from './config';
  jest.mock('./config');
  config.mockImplentation(() =&gt; ({
     foo: 'zed'
  }));
  </code></pre>
  
  <p>But its not mocking anything, and I am getting the config file as normal.</p>
  
  <p>What am I doing wrong?</p>