Merge pull request #12749 from iantropov/issue_5303

Add test for ActiveRecord::Relation YAML serialization, for #5303 issue

activerecord/test/cases/yaml_serialization_test.rb

@@ -43,4 +43,8 @@ def test_psych_roundtrip_new_object
     t = Psych.load Psych.dump topic
     assert_equal topic.attributes, t.attributes
   end
+
+  def test_active_record_relation_serialization
+    [Topic.all].to_yaml
+  end
 end