title: How can I import a module globally using jest config?
body: <p>I have a test file like:</p>
  <pre class="lang-js prettyprint-override"><code>let { expect } = chai;
  describe(...)
  </code></pre>
  <p>When I run jest, my test obviously fails with error chai is not defined. The simple solution is to import chai in each test file, but I prefer to find a better solution. Is there a way to import chai globally in jestConfig?</p>
  <p>I also tried <code>setupFiles</code> config to run a file which has imported chai, but didn't work.</p>