Question

JUnit Basic concepts needed

Asked by: cofactor

I am not familiar with JUnit . I was reading a Spring tutorial where I found they used JUnit in the tutorial  . So i need little Junit help to pass over that section and get going on the spring tutorial.

tutorial :
http://static.springsource.org/docs/Spring-MVC-step-by-step/part1.html#step1.9
 
see section  :   1.9. Write a test for the Controller

.Q1) I am surprised to see that they did not deploy the HelloController   in the server but tested the view  using JUnit !  ...thats interesting......but suppose instead of  HelloController  , if we had a HttpServlet ..can we still be able to test  without deploying the Httpservlet  in the server ?? I am asking because  Httpservlet  lives  inside the server ....So can we test a  Httpservlet without deploying it in the server using JUnit ?

Q2)
ModelAndView modelAndView = controller.handleRequest(null, null);      

why null,null ?  

Q3)
assertEquals("hello.jsp", modelAndView.getViewName());

modelAndView.getViewName());  
// how this can work upon ? controller is not yet deployed ..it cant respond....can it ??


Q4)
See the run output ...need to uderstand this
tests:
    [junit] Running springapp.web.HelloWorldControllerTests
    [junit] Oct 30, 2007 11:31:43 PM springapp.web.HelloController handleRequest
    [junit] INFO: Returning hello view
    [junit] Tests run: 1, Failures: 0, Errors: 0, Time elapsed: 0.03 sec
    [junit] Testsuite: springapp.web.HelloWorldControllerTests
    [junit] Tests run: 1, Failures: 0, Errors: 0, Time elapsed: 0.03 sec  //  WHY  TWICE PRINT ??

    [junit] ------------- Standard Error -----------------
    [junit] Oct 30, 2007 11:31:43 PM springapp.web.HelloController handleRequest
    [junit] INFO: Returning hello view // THIS IS NOT ERROR .WHY THIS IS UNDER  StandardError?
    [junit] ------------- ---------------- ---------------

Can you explain this run output ? I see there is some output  under  Standard Error  ...but that is not error ......and also "Tests run: 1" has been printed twice ....why ? does JUnit execute twice the test case to print two times ?


Q5) what it checks
assertNotNull(modelAndView.getModel());

looks like a null object checking ...if  it finds null ..does that going to throw some error under Standard Error  ??


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Asked On
2009-11-07 at 05:24:29ID24880362
Topics

Java Programming Language

,

Java Server Pages (JSP)

,

J2EE

Participating Experts
1
Points
500
Comments
4

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Answers

 

by: cofactorPosted on 2009-11-07 at 06:09:04ID: 25766374

comments please

 

by: mwvisa1Posted on 2009-11-07 at 19:54:13ID: 25769347

Unit testing a great way to ensure each segment of code is working as it should without the hassle of full deployment as you have seen.


Q1) As they have shown you can test the business logic separate from the HttpServlet (implementation) since your MVC should function the same whether the controller is executing on a web server or via some other protocol via socket for example.  However, being you are specifically dealing with Spring MVC and Servlets, to test the web application, you will find HttpUnit (http://httpunit.org) helpful also.


Q2) Take a look at the HelloController implementation.

public class HelloController implements Controller {

   protected final Log logger = LogFactory.getLog(getClass());

   public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException {

       logger.info("Returning hello view");

       return new ModelAndView("hello.jsp");
   }

}

Since it is for Servlet implementation, it takes HttpServletRequest and HttpServletResponse objects just like Servlet methods would.  Since you are testing with JUnit and not executing in a ServletContext and therefore are not receiving a request nor writing to a response, you can just pass null for both.  Hence:

ModelAndView modelAndView = controller.handleRequest(null, null);      


Q3) Referring again to the implementation above, see it returns a ModelAndView instance.  That is all that matters.  Doesn't matter this is running on web or on command line, as long as there is a valid ModelAndView that the getViewName() function can be called on and that the name of this view was "hello.jsp" then the assertion should be satisfied.


Q4) I typically am only looking for failures, issues; however, since there can be multiple tests in a test suite, IIRC, you will get trace for individual test which is the first and then the last is the suite completing for the overall test class completion.

FYI, it is not an error, it is result of logger.info().


Q5) It checks if the Model is set for the ModelAndView object.  Assert that the object is not null. :)
You would get a failure listed.


 

by: cofactorPosted on 2009-11-08 at 02:59:39ID: 25770106

I  am not clear on your explanations on Q1 , Q4

Q1)  did you mean JUnit / HttpUnit  can test   Controllers/HttpServlets  without  a deployment in the  server ?

I am asking because I take pain to deploy in the server and then I test  my web application through browser .....this kills some time ......So, i am thinking to use Junit to test my business logic without a deployment ....this is gonna save some time.

Can i use Junit/HttpJunit   to test my Servlet  ?

here is what my servlet does..

My servlet calls a DAO
DAO calls a DB
DB returns data to DAO
DAO returns data to Servlet
Servlet displays data on the browser.

Now ,  can i use Junit to print data in the servlet  without a deployment ??



Q4)
>>>> you will get trace for individual test which is the first and then the last is the suite >>completing for the overall test class completion.

in the tutorial We just had one test ..

assertEquals("hello.jsp", modelAndView.getViewName());

we get two prints because one for the individual test and another by the testsuite ...so  two prints ?

if that is so suppose,  if we had ..

assertEquals("hello.jsp", modelAndView.getViewName());
assertEquals("hello.jsp", modelAndView.getViewName());

Does that mean we would get  2+2 = 4 prints this time in total ?  is that correct ?

 

by: mwvisa1Posted on 2009-11-08 at 09:07:42ID: 25771008

"...Now ,  can i use Junit to print data in the servlet  without a deployment ??
..."

JUnit tests Java applications which is why they showed with HelloController which is not a servlet and since it takes parameters like a servlets then we pass null.

You can use HttpUnit to test web applications without deploying, though.  You can read more at the link I gave you.


"...Does that mean we would get  2+2 = 4 prints this time in total ?  is that correct ?..."

public class HelloControllerTests extends TestCase {

  // This is a single Test
  public void testHandleRequestView() throws Exception{            
             HelloController controller = new HelloController();
             ModelAndView modelAndView = controller.handleRequest(null, null);            
             assertEquals("hello.jsp", modelAndView.getViewName());
      }

  // This is another single Test
  public void testHandleRequestModel() throws Exception{            
             HelloController controller = new HelloController();
             ModelAndView modelAndView = controller.handleRequest(null, null);            
             assertNonNull(modelAndView.getModel());
      }
}

Together they are in the same test suite; therefore, you would get 1 display for each and then one more display indicating that all tests within the suite are completed (an overall results).  At least that is my understanding which you can test out for yourself.  The above should get 3 traces (2+1).

20120131-EE-VQP-002

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