How can we unit test a servlet with an embedded Jetty server?
For example, how to test the servlet method below?
protected void doGet(HttpServletRequest
You don't need Jetty to test the servlet, you need a unit testing framework, such as JUnit, Mockito, JMock, etc.
Generally speaking, you don't want to use a servlet container when you do unit testing because you want to focus your test on the actual method being tested, having jetty in the way means that you're also testing jetty behavior. After you've done all your unit tests you can move on to integration tests and system tests, and that part can involve external systems such as jetty (using automation frameworks such as Selenium.)
I use Mockito and PowerMock to do my unit testing, you can check out this code for a working example of a real online service (which you can find here). I wrote a tutorial about this service and what it contains, this can be found here.
[Added after getting downvotes from time to time on this answer]: And at the risk of getting even more downvotes, all you downvoters need to read the definition of UNIT TESTING before you click the -1 button. You just don't know what you're talking about.