Add test for module "Helper"

[kenboo0426]

Hi, Thank you for the great Gem!
I often use this gem!

Added Helper.policy_scope test to improve maintainability.
As a result, the test coverage changed from 98.41% to 100% in lib/pundit.rb

If there is a place to fix, please let me know.
best regards.

[Burgestrand]

Hi! Sorry about coming in this late.

I don't think we need to make any private instance methods public at all? Also the comment refers to protected methods but this does private methods.

What about this?

Suggested change

	include Pundit::Authorization
	include Pundit::Helper
	# Mark protected methods public so they may be called in test
	# rubocop:disable Style/AccessModifierDeclarations
	public(*Pundit::Authorization.private_instance_methods)
	# rubocop:enable Style/AccessModifierDeclarations
	def self.helper(mod)
	include(mod)
	end
	include Pundit::Authorization