Any test code that has $DONE() will be treated as an Async Test
Tests have an optional @timeour parameter that allows authors to
override the default timeout of 2000ms
$DONE() is used to indicate the test completion of the async test

Example
Test contains $DONE and defaultTimeoutvalue has been overriden to 10000ms

/*
 * @description This is a sample Test
  * @author NikSurya
   * @timeout 10000
    */

     Feature.OnComplete(function(){
          $DONE()
	   })