The Content with Style blog has continued their series looking at unit testing with the Zend Framework (see this previous post) with this look at testing services based models.

However, unit testing models that talk to web services presents us with a different set of problem. Usually our application runs requests against something that is not in our control. Unless the service provider gives us some kind of test mode, we're operating with dynamic live data which shouldn't be used for testing, since it's harder to test in the first place, but also could be harmful to be manipulated.

They present two method you can use to test the models: creating mock objects to handle and return correctly formatted data and intercepting the HTTP request to either send it to a Zend_HTTP adapter or a different endpoint (service location).