undefined method `registration_path' - devise (2.0.4) with Rails (3.2.2)

gistfile1.txt

# routes.rb
TestDevise::Application.routes.draw do
  devise_for :users
  root :to => 'welcome#index'
end

# rake routes
        new_user_session GET    /users/sign_in(.:format)       devise/sessions#new
            user_session POST   /users/sign_in(.:format)       devise/sessions#create
    destroy_user_session DELETE /users/sign_out(.:format)      devise/sessions#destroy
           user_password POST   /users/password(.:format)      devise/passwords#create
       new_user_password GET    /users/password/new(.:format)  devise/passwords#new
      edit_user_password GET    /users/password/edit(.:format) devise/passwords#edit
                         PUT    /users/password(.:format)      devise/passwords#update
cancel_user_registration GET    /users/cancel(.:format)        devise/registrations#cancel
       user_registration POST   /users(.:format)               devise/registrations#create
   new_user_registration GET    /users/sign_up(.:format)       devise/registrations#new
  edit_user_registration GET    /users/edit(.:format)          devise/registrations#edit
                         PUT    /users(.:format)               devise/registrations#update
                         DELETE /users(.:format)               devise/registrations#destroy
                    root        /                              welcome#index


# error
undefined method `registration_path' for #<#<Class:0x007f936ab09c08>:0x007f936b049088>

Extracted source (around line #3):

1: <h2>Sign up</h2>
2: 
3: <%= form_for(resource, :as => resource_name, :url => registration_path(resource_name)) do |f| %>
4:   <%= devise_error_messages! %>
5: 
6:   <div><%= f.label :email %><br />