How do you test a module that extends ActiveSupport::Concern?

Rails
1

I have a module that extends ActiveSupport::Concern. Here is the
included block:

included do
  after_save :save_tags

  has_many :taggings, :as => :taggable
  has_many :tags, :through => :taggings
end

How can I stub out these calls? I have tried a few ways, but Ruby
complains that these methods don’t exist when I try and test the
module in isolation.

Thanks!