Allow underscored attribute names other than the ones reserved by the HAL spec

lib/hyperclient/attributes.rb

@@ -9,13 +9,15 @@ module Hyperclient
   #   resource.attributes.title
   #
   class Attributes < Collection
+    RESERVED_PROPERTIES = [/^_links$/, /^_embedded$/] # http://tools.ietf.org/html/draft-kelly-json-hal#section-4.1
+
     # Public: Initializes the Attributes of a Resource.
     #
     # representation - The hash with the HAL representation of the Resource.
     #
     def initialize(representation)
       @collection = if representation.is_a?(Hash)
-                      representation.delete_if {|key, value| key =~ /^_/}
+                      representation.delete_if {|key, value| RESERVED_PROPERTIES.any? {|p| p.match(key) } }
                     else
                       representation
                     end

test/fixtures/element.json

@@ -19,6 +19,7 @@
     "title": "Real World ASP.NET MVC3",
     "description": "In this advanced, somewhat-opinionated production you'll get your very own startup off the ground using ASP.NET MVC 3...",
     "permitted": true,
+    "_hidden_attribute": "useful value",
     "_embedded": {
         "author": {
             "_links": {

test/hyperclient/attributes_test.rb

@@ -19,6 +19,20 @@ module Hyperclient
       attributes.wont_respond_to :_embedded
     end
 
+    it 'sets normal attributes' do
+      attributes.must_respond_to :permitted
+      attributes.permitted.must_equal true
+
+      attributes.must_respond_to :title
+      attributes.title.must_equal "Real World ASP.NET MVC3"
+    end
+
+    # Underscores should be allowed per http://tools.ietf.org/html/draft-kelly-json-hal#appendix-B.4
+    it 'sets _hidden_attribute as an attribute' do
+      attributes.must_respond_to :_hidden_attribute
+      attributes._hidden_attribute.must_equal 'useful value'
+    end
+
     it 'is a collection' do
       Attributes.ancestors.must_include Collection
     end

test/hyperclient/collection_test.rb

@@ -32,7 +32,7 @@ module Hyperclient
         name
       end
 
-      names.must_equal ['_links', 'title', 'description', 'permitted', '_embedded']
+      names.must_equal ['_links', 'title', 'description', 'permitted', '_hidden_attribute', '_embedded']
     end
 
     describe '#to_hash' do