detect private current_* methods

Some services may declare current_user (or current_* really) as private
methods if there is no need to expose that method in the controller.
Previously we would miss out on sending the user_id with the event if
this was the case, this change allows us to detect these as private
methods.

For testing purposes, we've made the current_* methods private since
that ensures we work with both private and public versions of these
methods.

lib/dfe/analytics/requests.rb

@@ -18,8 +18,8 @@ def trigger_request_event
                                              .with_response_details(response)
                                              .with_request_uuid(RequestLocals.fetch(:dfe_analytics_request_id) { nil })
 
-        request_event.with_user(current_user)           if respond_to? :current_user
-        request_event.with_namespace(current_namespace) if respond_to? :current_namespace
+        request_event.with_user(current_user)           if respond_to?(:current_user, true)
+        request_event.with_namespace(current_namespace) if respond_to?(:current_namespace, true)
 
         DfE::Analytics::SendEvents.do([request_event.as_json])
       end

spec/dummy/app/controllers/application_controller.rb

@@ -5,6 +5,8 @@ def index
     render plain: ''
   end
 
+  private
+
   def current_user
     Struct.new(:id).new(1)
   end