This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Personally, I'd test the functionality outside of the servlet. I use servlets (well, not really, but their equivalent) only to marshall data to service objects (or similar). I keep functionality isolated from the Servlet spec as much as possible to make testing easier.