title: Mocha Test Fails with AssertionError
body: <p>In JUnit (Java) the result of a unit test is either a succes, failure or error. </p>
  
  <p>When i try to run a test with Mocha  i either get a succes or assertion error. </p>
  
  <p>Is is normally to get an AssertionError for failure tests? (shouldn't it just be called an failure and not an error?)</p>
  
  <p><strong>AssertionError: -1 == 2
    + expected - actual</strong>  </p>
  
  <p>What about testing asynchronous code? When my tests fail i get an Uncaught eror? Is that normal? </p>
  
  <p>Like this: </p>
  
  <p><strong>Uncaught Error: expected 200 to equal 201</strong></p>