Java Extreme Programming Cookbook

Testing Cookies

Problem

You want to test a servlet that uses cookies.

Solution

Write a ServletTestCase that tests if your servlet correctly handles creating and managing cookies.

Discussion

Cookies are small pieces of information passed back and forth between the web server and the browser as a user navigates a web application. Web applications commonly use cookies for session tracking because a cookie’s value uniquely identifies the client. There is a danger for a web application to rely solely on cookies for session tracking because the user may, at any time, disable cookies. For this reason, you must design your web application so that your web application still works if cookies are disabled.

Cactus Proves that Code Works

Cactus provides some comfort when a test passes, because it passed while running in a servlet container. This fact helps prove the code actually works when deployed. This type of test is very useful when testing critical aspects of a web application—for example, session tracking. Session tracking usually mixes three technologies (or concepts): URL rewriting, cookies, and the servlet-session API. Typically, web applications use all three in order to provide a robust web application. Testing this part of a web application is challenging. By writing tests that execute in a servlet container, you are helping to guarantee that your code actually works as designed when deployed.

Example 7-5 shows how to write a test for a servlet that uses cookies to keep track of how ...