Scoping ActionController::Parameters doesn't work when passing a custom policy with with:

[louim]

Hey!

I came across a potential problem when scoping params with authorized_scope, when trying to use a specific policy, for example:

class CourseContentsController
  def create
    ...
    authorized_scope(params.require(:course_content), with: CoursePolicy)
    ...
  end
end

Will raise a ActionController::UnfilteredParameters: unable to convert unpermitted parameters to hash error.

Also related, but maybe not a bug, but the default implicit_authorization_target injected here:

action_policy/lib/action_policy/rails/controller.rb

Lines 54 to 56 in 7280473

	def implicit_authorization_target
	controller_name.classify.safe_constantize
	end

will output Couldn't find policy class for nil when unable to safe_constantize the controller. Maybe that is not possible, but I think it would be helpful for the message to read Couldn't find policy class for CourseContent or maybe a different message since it is not able to find a matching class?

I created a PR with failing tests to better demonstrate the issue.

[palkan]

Fixed and released in 0.3.1.

[louim]

Thank you! 🎉