Allow serialization of CollectionDecorators with ActiveModel::Serializers

Closes #471

draper.gemspec

@@ -10,7 +10,8 @@ Gem::Specification.new do |s|
   s.homepage    = "http://github.com/drapergem/draper"
   s.summary     = "View Models for Rails"
   s.description = "Draper adds an object-oriented layer of presentation logic to your Rails apps."
-  s.rubyforge_project = "draper"
+  s.license     = "MIT"
+
   s.files         = `git ls-files`.split("\n")
   s.test_files    = `git ls-files -- {test,spec,features}/*`.split("\n")
   s.executables   = `git ls-files -- bin/*`.split("\n").map{ |f| File.basename(f) }
@@ -27,5 +28,5 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'rspec-rails', '~> 2.12'
   s.add_development_dependency 'minitest-rails', '~> 0.2'
   s.add_development_dependency 'capybara'
-  s.license = "MIT"
+  s.add_development_dependency 'active_model_serializers'
 end

lib/draper/railtie.rb

@@ -44,6 +44,12 @@ module Draper
       end
     end
 
+    initializer "draper.setup_active_model_serializers" do |app|
+      ActiveSupport.on_load :active_model_serializers do
+        Draper::CollectionDecorator.send :include, ActiveModel::ArraySerializerSupport
+      end
+    end
+
     console do
       require 'action_controller/test_case'
       ApplicationController.new.view_context

spec/dummy/config/application.rb

@@ -9,6 +9,7 @@ require 'rails/all'
 require 'draper'
 attempt_require 'mongoid'
 attempt_require 'devise'
+require 'active_model_serializers'
 
 module Dummy
   class Application < Rails::Application

spec/dummy/spec/decorators/active_model_serializers_spec.rb

@@ -0,0 +1,11 @@
+require 'spec_helper'
+
+describe Draper::CollectionDecorator do
+  describe "#active_model_serializer" do
+    it "returns ActiveModel::ArraySerializer" do
+      collection_decorator = Draper::CollectionDecorator.new([])
+
+      expect(collection_decorator.active_model_serializer).to be ActiveModel::ArraySerializer
+    end
+  end
+end