Add test for helper assigning ivar called twice

If a method only assigns ivars, then there is no
reason to process method twice. It will be cached,
but we want to test case where we need the ivar
values from a cached method that does not depend
on environment.

test/apps/rails3.1/app/controllers/users_controller.rb

@@ -131,6 +131,10 @@ class UsersController < ApplicationController
     @other_thing = simple_helper_with_args(params[:x])
   end
 
+  def test_assign_twice
+    assign_ivar
+  end
+
   private
 
   def simple_helper

test/apps/rails3.1/app/views/users/test_assign_twice.html.erb

+<%= raw @some_value %>

test/apps/rails3.1/config/routes.rb

@@ -2,6 +2,7 @@ Rails31::Application.routes.draw do
   resources :users
   match 'users/test_simple_helper' => "users#test_simple_helper"
   match 'users/test_less_simple_helpers' => "users#test_less_simple_helpers"
+  match 'users/test_less_simple_helpers' => "users#test_assign_twice"
 
   resources :users do
     get 'mixin_action'

test/tests/test_rails31.rb

@@ -608,6 +608,15 @@ class Rails31Tests < Test::Unit::TestCase
       :file => /test_less_simple_helpers\.html\.erb/
   end
 
+  def test_xss_helper_assign_ivar_twice
+    assert_warning :type => :template,
+      :warning_type => "Cross Site Scripting",
+      :line => 1,
+      :message => /^Unescaped\ parameter\ value/,
+      :confidence => 0,
+      :file => /test_assign_twice\.html\.erb/
+  end
+
   def test_xss_helper_model_return
     assert_warning :type => :template,
       :warning_type => "Cross Site Scripting",