For documentation purposes (and double checking the tests) I'd add the negation of this test:
```ruby
it 'creates token even when there is already one (default)' do
  FactoryGirl.create(:access_token, :application_id => client.id, :resource_owner_id => owner.id)
  expect do
    subject.authorize
  end.to change { Doorkeeper::AccessToken.count }.by(1)
end
```