title: mocha global `before` that executes only 1 time
body: <p>I'm using mocha for node.js functional testing.</p>
  
  <p>There are several files in my test. </p>
  
  <p>How can I run a piece of code for only one time before all tests start?</p>
  
  <p>For example, I may have to set up a docker container before all tests start.
  Is it possible to do this with mocha?</p>
  
  <p>The <a href="https://mochajs.org/" rel="nofollow noreferrer"><code>before</code></a> hook runs 1 time for every test file. This doesn't meet my needs.</p>