Added method attribute_names

lib/virtus/class_methods.rb

@@ -49,6 +49,24 @@ def attributes
       attribute_set
     end
 
+    # Returns array of all attribute names defined on a Class
+    #
+    # @example
+    #   class User
+    #     include Virtus
+    #      
+    #     attribute :name, String
+    #     attribute :age, Integer
+    #   end
+    #
+    #   User.attribute_names # => [:name, :age]
+    #
+    # @return [Array]
+    # @api public
+    def attribute_names
+      attribute_set.map(&:name)
+    end
+
     private
 
     # Setup descendants' own Attribute-accessor-method-hosting modules

spec/unit/virtus/class_methods/finalize_spec.rb

@@ -64,4 +64,13 @@ class Address
   it 'automatically resolves constant when it is already available' do
     expect(Examples::Article.attribute_set[:person].type.primitive).to be(Examples::Person)
   end
+
+  describe 'attribute_names' do
+
+    it 'returns array of attribute names' do
+      expect(Examples::Person.attribute_names).to eq([:name, :articles, :address])
+    end
+
+  end
+
 end