In-container testing - JUnit in Action - page 127

Listing 8.1 Servlet implementing isAuthenticated

[...]
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

public class SampleServlet extends HttpServlet {
public boolean isAuthenticated(HttpServletRequest request) {
HttpSession session = request.getSession( false );
if (session == null ) {
return false ;
}
String authenticationAttribute =
(String) session.getAttribute("authenticated");
return Boolean.valueOf(authenticationAttribute).booleanValue();
}
}
This servlet, although simple enough, allows us to show the limitation of standard
unit testing. In order to test the method isAuthenticated , we need a valid Http-
ServletRequest . Because HttpServletRequest is an interface, we can't just call a
new HttpServletRequest . The HttpServletRequest lifecycle and implementation
are provided by the container (in this case, a servlet container.) The same is true for
other server-side objects like HttpSession . JU nit alone isn't enough to write a test
for the isAuthenticated method and for servlets in general.

DEFINITION Component and container —In this chapter, a component executes in
a container. A container offers services for the components it's hosting, such as
lifecycle, security, transaction, distribution, and so forth.

In the case of servlets and JSP s, the container is a servlet container like Jetty or Tomcat.
There are other types of containers, for example, EJB , database, and OSG i containers.
As long as a container creates and manages objects at runtime, we can't use stan-
dard JU nit techniques to test those objects.

8.2 The mock objects solution

We look at several solutions for in-container testing. The first solution for unit testing
the isAuthenticated method (listing 8.1) is to mock the HttpServletRequest class
using the approach described in chapter 7. Although mocking works, we need to write
a lot of code to create a test. We can achieve the same result more easily using the
open source EasyMock 1 framework (see chapter 7), as listing 8.2 demonstrates.

1

http://easymock.org/