Move Active Resource observer feature to this gem

This will make observers be an opt-in feature for users of
activeresource like it is for the other frameworks.

Author: rafaelfranca

Gemfile

@@ -3,5 +3,6 @@ source 'https://rubygems.org'
 # Specify your gem's dependencies in active_record-observers.gemspec
 gemspec
 gem 'rails', github: 'rails/rails', branch: '5-0-stable'
+gem 'activeresource', github: 'rails/activeresource'
 
 gem 'mocha', require: false

lib/rails/observers/active_resource/observing.rb

@@ -0,0 +1,41 @@
+require 'rails/observers/active_model/observing'
+
+module ActiveResource
+  module Observing
+    def self.prepended(context)
+      context.include ActiveModel::Observing
+    end
+
+    def create(*)
+      notify_observers(:before_create)
+      if result = super
+        notify_observers(:after_create)
+      end
+      result
+    end
+
+    def save(*)
+      notify_observers(:before_save)
+      if result = super
+        notify_observers(:after_save)
+      end
+      result
+    end
+
+    def update(*)
+      notify_observers(:before_update)
+      if result = super
+        notify_observers(:after_update)
+      end
+      result
+    end
+
+    def destroy(*)
+      notify_observers(:before_destroy)
+      if result = super
+        notify_observers(:after_destroy)
+      end
+      result
+    end
+  end
+end

lib/rails/observers/railtie.rb

@@ -17,6 +17,14 @@ class Railtie < ::Rails::Railtie
         end
       end
 
+      initializer "active_resource.observer" do |app|
+        ActiveSupport.on_load(:active_resourse) do
+          require 'rails/observers/active_resource/observing'
+
+          prepend ActiveResource::Observing
+        end
+      end
+
       config.after_initialize do |app|
         ActiveSupport.on_load(:active_record) do
           # Rails 5.1 forward-compat. AD::R is deprecated to AS::R in Rails 5.

rails-observers.gemspec

@@ -23,5 +23,6 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'activerecord', '>= 4.0', '< 5.1'
   s.add_development_dependency 'actionmailer', '>= 4.0', '< 5.1'
   s.add_development_dependency 'actionpack',   '>= 4.0', '< 5.1'
+  s.add_development_dependency 'activeresource', '>= 4.0', '< 5.1'
   s.add_development_dependency 'sqlite3',      '~> 1.3'
 end

test/active_resource_observer_test.rb

@@ -0,0 +1,63 @@
+require 'minitest/autorun'
+require 'active_resource'
+require 'rails/observers/active_resource/observing'
+
+ActiveResource::Base.prepend ActiveResource::Observing
+
+require 'active_support/core_ext/hash/conversions'
+
+class Person < ActiveResource::Base
+  self.site = "http://37s.sunrise.i:3000"
+end
+
+class ActiveResourceObservingTest < Minitest::Test
+  cattr_accessor :history
+
+  class PersonObserver < ActiveModel::Observer
+    observe :person
+
+    %w( after_create after_destroy after_save after_update
+        before_create before_destroy before_save before_update).each do |method|
+          define_method(method) { |*| log method }
+    end
+
+    private
+      def log(method)
+        (ActiveResourceObservingTest.history ||= []) << method.to_sym
+      end
+  end
+
+  def setup
+    @matz = { 'person' => { :id => 1, :name => 'Matz' } }.to_json
+
+    ActiveResource::HttpMock.respond_to do |mock|
+      mock.get    "/people/1.json", {}, @matz
+      mock.post   "/people.json",   {}, @matz, 201, 'Location' => '/people/1.json'
+      mock.put    "/people/1.json", {}, nil, 204
+      mock.delete "/people/1.json", {}, nil, 200
+    end
+
+    PersonObserver.instance
+  end
+
+  def teardown
+    self.history = nil
+  end
+
+  def test_create_fires_save_and_create_notifications
+    Person.create(:name => 'Rick')
+    assert_equal [:before_save, :before_create, :after_create, :after_save], self.history
+  end
+
+  def test_update_fires_save_and_update_notifications
+    person = Person.find(1)
+    person.save
+    assert_equal [:before_save, :before_update, :after_update, :after_save], self.history
+  end
+
+  def test_destroy_fires_destroy_notifications
+    person = Person.find(1)
+    person.destroy
+    assert_equal [:before_destroy, :after_destroy], self.history
+  end
+end