Fix preloading nil polymorphic belongs_to. Closes #11218 [matrix9180]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@8933 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

1 files changed, 7 insertions, 1 deletions

diff --git a/activerecord/test/cases/associations/join_model_test.rb b/activerecord/test/cases/associations/join_model_test.rb
index e72c6d0e07..e128d6dda3 100644
--- a/activerecord/test/cases/associations/join_model_test.rb
+++ b/activerecord/test/cases/associations/join_model_test.rb
@@ -331,7 +331,7 @@ class AssociationsJoinModelTest < ActiveRecord::TestCase
     assert_no_queries do
       assert_equal desired, tag_with_include.tagged_posts
     end
-    assert_equal 4, tag_with_include.taggings.length
+    assert_equal 5, tag_with_include.taggings.length
   end
 
   def test_has_many_through_has_many_find_all
@@ -589,6 +589,12 @@ class AssociationsJoinModelTest < ActiveRecord::TestCase
     assert taggables.include?(posts(:welcome))
   end
 
+  def test_preload_nil_polymorphic_belongs_to
+    assert_nothing_raised do
+      taggings = Tagging.find(:all, :include => :taggable, :conditions => ['taggable_type IS NULL'])
+    end
+  end
+
   def test_preload_polymorphic_has_many
     posts               = Post.find(:all, :order => 'posts.id')
     posts_with_taggings = Post.find(:all, :include => :taggings, :order => 'posts.id')