title: create-react-app: use a proxy for Jest tests
body: <p>I want to use an actual API for my react Jest tests. Because the test environment is JSDom, I can't make cross-origin requests. In development this is easily solved by specifying a proxy in the package.json file, however this does not apply to the test suite run through: <code>npm test</code>.</p>
  
  <p>I know that it is possible to specify a proxy when creating a new JSDom instance using (<a href="https://github.com/jsdom/jsdom#advanced-configuration" rel="nofollow noreferrer">see docs</a>):</p>
  
  <pre><code>const resourceLoader = new jsdom.ResourceLoader({
    proxy: "http://127.0.0.1:9001",
  });
  </code></pre>
  
  <p>Now I can't find a way to use this with my applicatio, which is created using create-react-app (CRA)... So my question is, is there some way to specify a proxy when running Jest through a CRA app?</p>
  
  <p>Thanks!</p>