如何从Servlet发送响应

Question

I have a Ajax call sent from browser to a Servlet. At Servlet some value is calculated say A. My query is how can I validate this A. I am using TestNG from where the browser starts but after that control shifts to Servlet. How should I return the value from Servlet such that in TestNG I can fetch it and validate.

Answer 1

solutions I can think of:

(1) 

Bypass the servlet: put your business calculations in a separate method/class, and test directly. This might be enough if the focus is on the business code (while the servlet layer does trivial tasks such as extracting simple request parameters). Eg:

// logic - assuming this is the test focus, with interesting cases such as insufficient funds, limited account etc.
public class MyBank{
   public void transferFunds(int fromAccountId, int toAccountId, int dollars)...   
}
// servlet that happens to have trivial code that isn't so important to test
public class MyServlet{
    ...
         int fromAccountId=Integer.parseInt(req.getParameter("fromAccountId"));
         int toAccountId=Integer.parseInt(req.getParameter("toAccountId"));
         int dollars= Integer.parseInt(req.getParameter("dollars"));
         bank.transferFunds(fromAccountId, toAccountId, dollars)
}

(2) Use an embedded server, like Jetty. http://www.eclipse.org/jetty/documentation/current/embedding-jetty.html From your unit test you just launch a jetty (using 'new Server()'...) and tell it to execute the servlet.

(3) you can also invoke your servlet, injecting it with mock request/response/session etc. Spring, for example, has such mock objects. So it's something like:

HttpServletRequest mockReq=new MockHttpServletRequest();
HttpServletRequest mockResp=new MockHttpServletResponse();
new MyServlet().service(mockReq, mockResp);

Just note it might require some tweaking depending on what your servlet needs - eg request parameters, session (the mock request has methods to add them)