title: How to set execution order of mocha test cases in multiple files
body: <p>I have two javascript files which contain mocha test cases. </p>
  
  <pre><code>//----------abc.js -------------
  
  describe("abc file", function(){
    it("test 1" , function(){
      assert.equal(20 , 20); 
    });
  }); 
  
  //---------xyz.js--------------
  describe("xyz file", function(){
        it("test 1" , function(){
          assert.equal(10 , 10); 
        });
      });
  </code></pre>
  
  <p>I have put them in a folder called <code>test</code> and when I execute the <code>mocha</code> command the first file(abc.js) is always executed before xyz.js.
  I thought this might be due to alphabetical ordering and renamed the files as</p>
  
  <pre><code>abc.js =&gt; xyz.js
  xyz.js =&gt; abc.js
  </code></pre>
  
  <p>but still, the content of the xyz.js (previously abc.js) is executed first. How can I change the execution order of these test files?</p>