use #described_class, as suggested by RuboCop

spec/policies/application_policy_spec.rb

@@ -4,7 +4,7 @@ describe ApplicationPolicy do
   describe '#initialize' do
     context 'without a user' do
       it 'raises an error' do
-        expect { ApplicationPolicy.new(nil, nil) }.to raise_error(Pundit::NotAuthorizedError)
+        expect { described_class.new(nil, nil) }.to raise_error(Pundit::NotAuthorizedError)
       end
     end
   end