title: What should I do for this error: require('connect').json() is undefined
body: <p>When I typed <code>gulp test</code>, I get this error: <code>require('connect').json() is undefined.</code>. What should I do?</p>
  
  <p>The detail error message as following:</p>
  
  <pre><code> tianjiedeMacBook-Pro:meiyanapp tianjie$ gulp test
   /Users/tianjie/meiyanruhua/meiyanapp/node_modules/karma/lib/middleware/runner.js:11
   var json = require('connect').json();
                                 ^ TypeError: undefined is not a function
       at Object.&lt;anonymous&gt; (/Users/tianjie/meiyanruhua/meiyanapp/node_modules/karma/lib/middleware/runner.js:11:31)
       at Module._compile (module.js:460:26)
       at Object.Module._extensions..js (module.js:478:10)
       at Module.load (module.js:355:32)
       at Function.Module._load (module.js:310:12)
       at Module.require (module.js:365:17)
       at require (module.js:384:17)
       at Object.&lt;anonymous&gt; (/Users/tianjie/meiyanruhua/meiyanapp/node_modules/karma/lib/web-server.js:7:24)
       at Module._compile (module.js:460:26)
       at Object.Module._extensions..js (module.js:478:10)
  </code></pre>