Add "scope" method

test/serializer_test.rb

@@ -94,6 +94,11 @@ class SerializerTest < ActiveModel::TestCase
     has_many :comments, :serializer => CommentSerializer
   end
 
+  def test_scope_works_correct
+    serializer = ActiveModel::Serializer.new :foo, :scope => :bar
+    asser_equal serializer.scope, :bar
+  end
+
   def test_attributes
     user = User.new
     user_serializer = DefaultUserSerializer.new(user, {})