Mimic an HTTPRequest and HTTPResponse object in Java

Question

How do I mimic an HTTPServletRequest and HTTPServletResponse object. The reason is I want to test the behaviour of some servlets.

I know JUnit probably provides this functionality but I don't know how to use it (I will learn soon) and need to do this reasonably quickly.

HTTPServletRequest and HTTPServletResponse are both interfaces so they can't be instantiated. There is a HttpServletRequestWrapper which implements HttpServletRequest but it doesn't seem to have any setParameter() type methods and HttpServletResponse doesn't seem to have any implementing classes at all.

How can I test my code by passing a suitable HttpServletRequest object and then checking that the received HttpServletResponse object matches what I expect?

Answer 1

The fact that it's an interface makes it easier to mimic: It's mocking final classes that's tricky.

class MyHttpServletRequest implements HttpServletRequest
{
  //whatever
}

class MyHttpServletResponse implements HttpServletResponse
{
  //whatever
}


doGet(new MyHttpServletRequest(),
      new MyHttpServletResponse())

Subclassing HttpServletRequestWrapper may be easier, but it's not necessary. I would look at overriding getParameter and getParameterMap

Answer 2

Create a dummy object:

class MyDummyRequest implements HTTPServletRequest{
    //implement your own methods, for example:
    public Map getParameterMap(){
        Map myMap = new HashMap();
        //put the params you need inside myMap
        return myMap;
    }
}

If you want to avoid creating dummy objects for test purposes you may look into one of the available mocking libraries for Java, such as Mockito.