On the ZendCasts.com site today there's a new screencast posted showing you how to use Zend_Test to unit test the action helpers in your Zend Framework application.
A look at how action helpers function and effective ways of unit testing them.
The Zend_Test allows for simpler integration of PHPUnit tests with Zend Framework-based applications. He shows how to set up a bootstrap file to initialize the framework, create a simple test on his "Signup" action helper and output the code coverage report to help you get a better sense for how much of your code has tests written for it.