Testing Behaviors

Attempting to test a product that adds schema to a dexterity type. I've enabled the behavior via the instructions found on Testing a dexterity type with a behavior. When I access the content type, I see that my behavior interface is providedBy the object, but the attributes supplied by the schema do not exist. The behavior appears to work fine in a bare site when applied to the type through the web, just not in testing. I am applying the code in the setUp of my tests.

fti = queryUtility(IDexterityFTI, name='pre.existing.contenttype')
behaviors = list(fti.behaviors)
behaviors.append(INewBehavior.__identifier__)
fti.behaviors = tuple(behaviors)
notify(SchemaInvalidatedEvent('pre.existing.contenttype'))

Am I missing a step? The documentation above is straight forward.

We do something similar here: