diff --git a/plugins/ckeditor_content/test/test_helper.rb b/plugins/ckeditor_content/test/test_helper.rb
index cca1fd3..b25011a 100644
--- a/plugins/ckeditor_content/test/test_helper.rb
+++ b/plugins/ckeditor_content/test/test_helper.rb
@@ -1 +1,5 @@
 require File.dirname(__FILE__) + '/../../../test/test_helper'
+
+def assert_subclass(parent, child)
+  assert_equal parent, child.superclass, "Class #{child} expected to be a subclass of #{parent}"
+end
--
libgit2 0.21.2