How to mock a RemoteServiceServlet with HttpRequestSession - gwt

Question

Here is a code snippet of my RemoteServiceServlet. The function getSubject(), obtains the session from the HttpServletRequest, which refers to the getThreadLocalRequest. I am making a junit test to test this server, however the getThreadLocalRequest is not populated and returns null.
public class Server extends XsrfProtectedServiceServlet implements RemoteInterface {
private static final long serialVersionUID = 2230123191888380541L;
public Server() throws IOException
{
credentials = new PropertiesCredentials(Server.class.getResourceAsStream("AwsCredentials.properties.email"));
database = new Database();
}
public Subject getSubject()
{
HttpServletRequest request = this.getThreadLocalRequest();
HttpSession session = request.getSession(false);
Subject subject = (Subject)session.getAttribute("subject");
return subject;
}
}
This is my junit test
#Test
public void testserver()
{
Server s = new Server();
s.getSubject();
}
s.getSubject fails because the session is not populated. How can I mock Server so that I can populate a session.

Answer 1

You'll need to use a mocking framework to create behaviour around the object under test. I use PowerMock with EasyMock (http://code.google.com/p/powermock/).
What I suggest you do first, though, is refactor the code out of the constructor. As written, this code is very complicated to test, because the getResourceAsStream method is a static method of the underlying Class type. And since it's not used in the method under test (nor is the database reference), I question the need to use the constructor to get the resource bundle.
To test your getSubject() method, essentially what you need to do is create an instance of your class that is a partial mock, where the getThreadLocalRequest is the only method to be mocked:
#RunWith( PowerMockRunner.class )
#PrepareForTest( Server.class )
public class ServerTest {
#Test
public void testGetSubjectReturnsSubjectFromHttpSession() {
// assuming the constructor is cleaned up, create a Server instance...
Server server = PowerMock.createPartialMockAndInvokeDefaultConstructor( Server.class, "getThreadLocalRequest" );
// create a mock object that represents the Http request
HttpServletRequest mockRequest = PowerMock.createMock(HttpServletRequest.class);
EasyMock.expect( server.getThreadLocalRequest() ).andReturns( mockRequest);
// create a mock for the Http Session
HttpSession mockSession = PowerMock.createMock( HttpSession.class );
EasyMock.expect( mockRequest.getSession( EasyMock.anyBoolean() ) ).andReturns( mockSession );
EasyMock.expect( mockSession.getAttribute( EasyMock.isA( String.class ) ).andReturns( mockSubject );
// put the mocks into playback mode
PowerMock.replayAll();
// exercise the method
Subject subject = server.getSubject();
// verify that the mocks were called as you expect them to be...
PowerMock.verifyAll();
// and here you put other assertions that relate to the data returned...
Assert.assertNotNull( subject );
}
}