Userstamp plugin doesn't load in "test" environment - y not?

I'm working on an app. with the userstamp plugin in it (from 2 - 3 years
back).

In the init.rb file, there's this:

ActiveRecord::Base.send(:include, ActiveRecord::Userstamp) unless
RAILS_ENV == 'test'

This causes certain tests to fail since created_by is a required
attribute.

Does anyone know the idea behind Userstamp not loading in the test
environment. I'm just curious.

Thanks,
Wes