The example code for this tutorial, Unit_Testing_Struts2_Mvn, is available on Google Code - http://code.google.com/p/struts2-examples/downloads/list. After downloading and unzipping the file, you'll have a folder named Unit_Testing_Struts2_Mvn. In that folder will be a README.txt file with instructions on now to build and run the example application.
Introduction
Struts 2 supports running unit tests of method in the Struts Action class with the Struts 2 JUnit plugin.
The Struts 2 user mailing list is an excellent place to get help. If you are having a problem getting the tutorial example applications to work search the Struts 2 mailing list. If you don't find an answer to your problem, post a question on the mailing list.