This blog post provides a detail process on how to create and run unit tests for Google App Engine applications. The author shows how to write the tests using the standard python unittest module and execute them with gaeunit, a web based test runner. He reminds us that it is easier to write unit tests during design rather than afterwards. We should also keep the tests high level so that further detailed modifications will not break the tests. A short video summarizing Google App Engine unit testing is available at the end.