diff --git a/actionpack/lib/action_controller/metal/helpers.rb b/actionpack/lib/action_controller/metal/helpers.rb
index a9c3e438fb95d..819837e767155 100644
--- a/actionpack/lib/action_controller/metal/helpers.rb
+++ b/actionpack/lib/action_controller/metal/helpers.rb
@@ -93,6 +93,10 @@ def modules_for_helpers(args)
         super(args)
       end
 
+      # Return a list of helper names in specific path.
+      #
+      #   ActionController::Base.all_helpers_from_path 'app/helpers'
+      #   # => ["application", "chart", "rubygems"]
       def all_helpers_from_path(path)
         helpers = Array(path).flat_map do |_path|
           extract = /^#{Regexp.quote(_path.to_s)}\/?(.*)_helper.rb$/