serializable_hash(:only => [], :methods => [:foo]) should work

activemodel/lib/active_model/serialization.rb

@@ -69,14 +69,11 @@ module Serialization
     def serializable_hash(options = nil)
       options ||= {}
 
-      only   = Array.wrap(options[:only]).map(&:to_s)
-      except = Array.wrap(options[:except]).map(&:to_s)
-
       attribute_names = attributes.keys.sort
-      if only.any?
-        attribute_names &= only
-      elsif except.any?
-        attribute_names -= except
+      if only = options[:only]
+        attribute_names &= Array.wrap(only).map(&:to_s)
+      elsif except = options[:except]
+        attribute_names -= Array.wrap(except).map(&:to_s)
       end
 
       method_names = Array.wrap(options[:methods]).map { |n| n if respond_to?(n.to_s) }.compact

activemodel/test/cases/serialization_test.rb

@@ -42,4 +42,14 @@ def test_method_serializable_hash_should_work_with_methods_option
     assert_equal expected , @user.serializable_hash(:methods => [:foo])
   end
 
+  def test_method_serializable_hash_should_work_with_only_and_methods
+    expected =  {:foo=>"i_am_foo"}
+    assert_equal expected , @user.serializable_hash(:only => [], :methods => [:foo])
+  end
+
+  def test_method_serializable_hash_should_work_with_except_and_methods
+    expected =  {"gender"=>"male", :foo=>"i_am_foo"}
+    assert_equal expected , @user.serializable_hash(:except => [:name, :email], :methods => [:foo])
+  end
+
 end