Add a deprecation for helpers_dir.

actionpack/lib/action_controller/metal/helpers.rb

@@ -56,6 +56,18 @@ module Helpers
     end
 
     module ClassMethods
+      def helpers_dir
+        ActiveSupport::Deprecation.warn "ActionController::Base.helpers_dir is deprecated. " <<
+          "Please use ActionController::Base.helpers_path (which returns an array)"
+        self.helpers_path
+      end
+
+      def helpers_dir=(value)
+        ActiveSupport::Deprecation.warn "ActionController::Base.helpers_dir= is deprecated. " <<
+          "Please use ActionController::Base.helpers_path= (which is an array)"
+        self.helpers_path = Array(value)
+      end
+
       def inherited(klass)
         klass.class_eval { default_helper_module! unless name.blank? }
         super

actionpack/test/controller/helper_test.rb

@@ -31,7 +31,7 @@ def b() end
   def c() end
 end
 
-class HelperTest < Test::Unit::TestCase
+class HelperTest < ActiveSupport::TestCase
   class TestController < ActionController::Base
     attr_accessor :delegate_attr
     def delegate_method() end
@@ -135,6 +135,17 @@ def test_helper_proxy
     assert methods.include?('foobar')
   end
 
+  def test_deprecation
+    assert_deprecated do
+      ActionController::Base.helpers_dir = "some/foo/bar"
+    end
+    assert_deprecated do
+      assert_equal ["some/foo/bar"], ActionController::Base.helpers_dir
+    end
+  ensure
+    ActionController::Base.helpers_path = [File.dirname(__FILE__) + '/../fixtures/helpers']
+  end
+
   private
     def expected_helper_methods
       TestHelper.instance_methods.map {|m| m.to_s }
@@ -154,7 +165,7 @@ def test_helper=(helper_module)
 end
 
 
-class IsolatedHelpersTest < Test::Unit::TestCase
+class IsolatedHelpersTest < ActiveSupport::TestCase
   class A < ActionController::Base
     def index
       render :inline => '<%= shout %>'