If you want to find out how to test you GAE apps, check out these two URLs first:
http://groups.google.com/group/google-appengine/msg/9132b44026040498
http://farmdev.com/thoughts/45/testing-google-app-engine-sites/
I want to show you how to clear the datastore quickly (yep, only that :>):
from google.appengine.api import apiproxy_stub_map
def clear_datastore():
datastore = apiproxy_stub_map.apiproxy.GetStub('datastore_v3')
datastore.Clear()
