Relation#respond_to? should take second argument for responding to private methods

activerecord/lib/active_record/relation.rb

@@ -142,8 +142,8 @@ def where(*args)
       create_new_relation(@relation.where(conditions))
     end
 
-    def respond_to?(method)
-      return true if @relation.respond_to?(method) || Array.method_defined?(method)
+    def respond_to?(method, include_private = false)
+      return true if @relation.respond_to?(method, include_private) || Array.method_defined?(method)
 
       if match = DynamicFinderMatch.match(method)
         return true if @klass.send(:all_attributes_exists?, match.attribute_names)

activerecord/test/cases/relations_test.rb

@@ -146,6 +146,13 @@ def test_scoped_responds_to_delegated_methods
     end
   end
 
+  def test_respond_to_private_arel_methods
+    relation = Topic.scoped
+
+    assert ! relation.respond_to?(:matching_attributes)
+    assert relation.respond_to?(:matching_attributes, true)
+  end
+
   def test_respond_to_dynamic_finders
     relation = Topic.scoped