[Zope] Unit Testing

Has somebody successfully used ZUnit to test a TTW Zope Product and if you have can you give me some pointers. I thought if I could get a handle on Zope.app() in 'n TestSuite then one should be able to test methods in Zope quite easily. The only variable that seems to expose a bit of the zope context is ZopeContext but that points only to the TestFolderInstance and I can't get a handle on any other objects. Or should one stick with ZPublisher.Test? Roché