HttpUnit
Build a Java Web App Using HttpUnit and the Test-driven Methodology, Part I
Unit performs automated testing for standalone Java applications that either run on the command line or serve as components. If you develop large-scale or distributed applications, however, you are most likely going to work with Java Web applications. Because Web applications communicate via HTTP rather than Java method calls, JUnit is poorly equipped to test Web applications. HttpUnit comes to the rescue. This freely available toolprovides Web testing functionality that complements JUnit.
Don't forget about JWebUnit. I think it's a lot easier to work with.
Unit performs automated testing for standalone Java applications that either run on the command line or serve as components. If you develop large-scale or distributed applications, however, you are most likely going to work with Java Web applications. Because Web applications communicate via HTTP rather than Java method calls, JUnit is poorly equipped to test Web applications. HttpUnit comes to the rescue. This freely available toolprovides Web testing functionality that complements JUnit.
Don't forget about JWebUnit. I think it's a lot easier to work with.