Dasherize XML root by default to avoid invalid tags...

Dasherize XML root by default to avoid invalid tags "<admin/posts>...</admin/posts>" [#2875 state:resolved]

activemodel/lib/active_model/serializers/xml.rb

@@ -90,7 +90,7 @@ def builder
         end
 
         def root
-          root = (options[:root] || @serializable.class.to_s.underscore).to_s
+          root = (options[:root] || @serializable.class.model_name.singular).to_s
           reformat_name(root)
         end
 

activemodel/test/cases/serializeration/xml_serialization_test.rb

@@ -9,6 +9,11 @@ def attributes
   end
 end
 
+module Admin
+  class Contact < ::Contact
+  end
+end
+
 class XmlSerializationTest < ActiveModel::TestCase
   def setup
     @contact = Contact.new
@@ -25,6 +30,12 @@ def setup
     assert_match %r{</contact>$}, @xml
   end
 
+  test "should serialize namespaced root" do
+    @xml = Admin::Contact.new(@contact.attributes).to_xml
+    assert_match %r{^<admin-contact>},  @xml
+    assert_match %r{</admin-contact>$}, @xml
+  end
+
   test "should serialize default root with namespace" do
     @xml = @contact.to_xml :namespace => "http://xml.rubyonrails.org/contact"
     assert_match %r{^<contact xmlns="http://xml.rubyonrails.org/contact">}, @xml

activemodel/test/models/contact.rb

 class Contact
   attr_accessor :name, :age, :created_at, :awesome, :preferences
+
+  def initialize(options = {})
+    options.each { |name, value| send("#{name}=", value) }
+  end
 end