title: how to pass a test with expect.js async done() taking an error?
body: <p>Mocha website states:</p>
  
  <p>"To make things even easier, the done() callback accepts an error, so we may use this directly: [see their example]"</p>
  
  <p>So lets try that:</p>
  
  <pre class="lang-js prettyprint-override"><code>it('works',function(done){
    expect(1).to.be(1)
    done( new Error('expected error') )
  })
  /* Insert the error manually for testing and clarity. */
  </code></pre>
  
  <p>run it and:</p>
  
  <pre class="lang-js prettyprint-override"><code>1 failing
  
  1) works:
   Error: expected error
    at Context.&lt;anonymous&gt;
    [stack trace]
  </code></pre>
  
  <p>How do we make the test pass when the error response is the desired result?</p>