title: Mocha runs correctly, but shows undefined
body: <p>I use <code>mocha</code> to test my nodejs code, and the test runs just ok, but when I use <code>mocha test.js</code> to run test, it seems that the string I passed to <code>describe</code> does not show.</p>
  
  <p>The code is as follows:</p>
  
  <pre><code>var assert = require("should");
  describe("FrontEndTest", function(){
      describe('websocket establish connection', function(){
          it('should establish connection correctly', function(done){
              var res;
              var wsClient = create_ws_client('ws://127.0.0.1:9876','brain_burst');
              wsClient.on('connect', function(connection){
                  res = true;
                  res.should.be.true;
                  done();
              });
              wsClient.on('connectFailed', function(error){
                  res = false;
                  res.should.be.true;
                  done();
              });
              console.log(res);
          });
          it('should disconnected by server.(also, that may crash server if there is not a protocol validation)', function(done){
              var res;
              var wsClient = create_ws_client('ws://127.0.0.1:9876');
              wsClient.on('connect', function(connection){
                  res = true;
                  res.should.be.false;
                  done();
              });
              wsClient.on('connectFailed', function(error){
                  res = false;
                  res.should.be.false;
                  done();
              });
          });
      });
  });
  </code></pre>
  
  <p>The result of <code>mocha</code> command shows:</p>
  
  <blockquote>
    <p>undefined ․․</p>
    
    <p>✔ 2 tests complete (68 ms)</p>
  </blockquote>
  
  <p>Why it shows <code>undefined</code> since I already pass a string?</p>