From 9d066bc9417b06c8eaa8a7e5e73b153093102bbc Mon Sep 17 00:00:00 2001
From: Douwe Maan <douwe@gitlab.com>
Date: Thu, 8 Oct 2015 13:00:15 +0200
Subject: [PATCH] Raise error when a ReferenceFilter doesn't implement
 referenced_by

---
 lib/gitlab/markdown/reference_filter.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/gitlab/markdown/reference_filter.rb b/lib/gitlab/markdown/reference_filter.rb
index d334a891509..c7d4b15d458 100644
--- a/lib/gitlab/markdown/reference_filter.rb
+++ b/lib/gitlab/markdown/reference_filter.rb
@@ -25,7 +25,7 @@ module Gitlab
       end
 
       def self.referenced_by(node)
-        nil
+        raise NotImplementedError, "#{self} does not implement #{__method__}"
       end
 
       # Returns a data attribute String to attach to a reference link
-- 
GitLab