Support polymorphic_name

`polymorphic_name` was introduced in 5.2.0 but wasn't properly ported to CPK.

lib/composite_primary_keys/associations/association.rb

@@ -11,8 +11,8 @@ def creation_attributes
             attributes[key1] = owner[key2]
           end
 
-          if reflection.options[:as]
-            attributes[reflection.type] = owner.class.base_class.name
+          if reflection.type
+            attributes[reflection.type] = owner.class.polymorphic_name
           end
         end
 

lib/composite_primary_keys/associations/association_scope.rb

@@ -64,4 +64,4 @@ def next_chain_scope(scope, reflection, next_reflection)
       end
     end
   end
-end
+end

test/fixtures/comments.yml

@@ -15,3 +15,9 @@ user_comment_2:
   article: second
   person_id: 2
   person_type: User
+
+user_comment_3:
+  id: 4
+  article: first
+  person_id: 1
+  person_type: User1

test/fixtures/user_with_polymorphic_name.rb

@@ -0,0 +1,9 @@
+class UserWithPolymorphicName < ActiveRecord::Base
+  self.table_name = "users"
+
+  has_many :comments, :as => :person
+
+  def self.polymorphic_name
+    "User1"
+  end
+end

test/test_polymorphic.rb

@@ -40,4 +40,10 @@ def test_clear_has_many_through
     article.user_commentators = []
     assert_equal(0, article.comments.size)
   end
+
+  def test_polymorphic_has_many_with_polymorphic_name
+    comments = UserWithPolymorphicName.find(1).comments
+    assert_equal 1, comments[0].person_id
+    assert_equal "User1", comments[0].person_type
+  end
 end