I admit I don't follow Zend Framework very closely, since I haven't been using it for any serious work.But I did write a piece about testing a Zend Framework action controller with View Helpers.

This might need updating, since the testing capabilities of the Zend Framework have grown substantially since then. In particular, there is now a component called Zend_Test. I haven't had time to study it closely yet, but I hope to do so soon.