You can use Doorkeeper models in your application test suite. Note that starting from Doorkeeper 4.3.0 it uses ActiveSupport lazy loading hooks to load models. There are known issue with the factory_bot_rails gem (it executes factories building before ActiveRecord::Base is initialized using hooks in gem railtie, so you can catch a uninitialized constant error). It is recommended to use pure factory_bot gem to solve this problem.