remove rails-observers

Rails yanked out observers many many years ago, instead the functionality
was yanked out to a gem that is very lightly maintained.

For example: if we want to upgrade to rails 5 there is no published gem

Internally the usage of observers had quite a few problem.

The series of refactors renamed a bunch of classes to give us more clarity
and removed some magic.

spec/components/post_creator_spec.rb

@@ -5,7 +5,6 @@ require 'topic_subtype'
 describe PostCreator do
 
   before do
-    ActiveRecord::Base.observers.enable :all
   end
 
   let(:user) { Fabricate(:user) }

spec/components/post_destroyer_spec.rb

@@ -4,7 +4,6 @@ require 'post_destroyer'
 describe PostDestroyer do
 
   before do
-    ActiveRecord::Base.observers.enable :all
     UserActionCreator.enable
   end
 

spec/controllers/user_actions_controller_spec.rb

@@ -9,7 +9,6 @@ describe UserActionsController do
     end
 
     it 'renders list correctly' do
-      ActiveRecord::Base.observers.enable :all
       UserActionCreator.enable
       post = Fabricate(:post)
 

spec/models/category_user_spec.rb

@@ -68,7 +68,6 @@ describe CategoryUser do
 
   context 'integration' do
     before do
-      ActiveRecord::Base.observers.enable :all
       NotificationEmailer.enable
     end
 

spec/models/directory_item_spec.rb

@@ -20,7 +20,6 @@ describe DirectoryItem do
 
   context 'refresh' do
     before do
-      ActiveRecord::Base.observers.enable :all
       UserActionCreator.enable
     end
 

spec/models/notification_spec.rb

@@ -2,7 +2,6 @@ require 'rails_helper'
 
 describe Notification do
   before do
-    ActiveRecord::Base.observers.enable :all
     NotificationEmailer.enable
   end
 
@@ -235,7 +234,6 @@ describe Notification do
   describe 'ensure consistency' do
     it 'deletes notifications if post is missing or deleted' do
 
-      ActiveRecord::Base.observers.disable :all
       NotificationEmailer.disable
 
       p = Fabricate(:post)

spec/models/post_action_spec.rb

@@ -220,7 +220,9 @@ describe PostAction do
   describe 'when a user likes something' do
 
     it 'should generate notifications correctly' do
-      ActiveRecord::Base.observers.enable :all
+
+      PostActionNotifier.enable
+
       PostAction.act(codinghorror, post, PostActionType.types[:like])
       expect(Notification.count).to eq(1)
 

spec/models/post_mover_spec.rb

@@ -31,8 +31,6 @@ describe PostMover do
     before do
       p1.replies << p3
       p2.replies << p4
-      # add a like to a post, enable observers so we get user actions
-      ActiveRecord::Base.observers.enable :all
       UserActionCreator.enable
       @like = PostAction.act(another_user, p4, PostActionType.types[:like])
     end

spec/models/post_timing_spec.rb

@@ -81,8 +81,7 @@ describe PostTiming do
     # integration test
 
     it 'processes timings correctly' do
-
-      ActiveRecord::Base.observers.enable :all
+      PostActionNotifier.enable
 
       post = Fabricate(:post)
       user2 = Fabricate(:coding_horror, created_at: 1.day.ago)

spec/models/site_spec.rb

@@ -3,9 +3,6 @@ require_dependency 'site'
 
 describe Site do
   it "omits categories users can not write to from the category list" do
-
-    ActiveRecord::Base.observers.enable :anon_site_json_cache_observer
-
     category = Fabricate(:category)
     user = Fabricate(:user)
 

spec/models/tag_user_spec.rb

@@ -68,12 +68,7 @@ describe TagUser do
   end
 
   context "integration" do
-    before do
-      ActiveRecord::Base.observers.enable :all
-    end
-
     let(:user) { Fabricate(:user) }
-
     let(:watched_tag) { Fabricate(:tag) }
     let(:muted_tag)   { Fabricate(:tag) }
     let(:tracked_tag) { Fabricate(:tag) }

spec/models/topic_spec.rb

@@ -429,7 +429,6 @@ describe Topic do
       let(:actions) { topic.user.user_actions }
 
       it "should set up actions correctly" do
-        ActiveRecord::Base.observers.enable :all
         UserActionCreator.enable
 
         expect(actions.map{|a| a.action_type}).not_to include(UserAction::NEW_TOPIC)

spec/models/topic_user_spec.rb

@@ -208,7 +208,6 @@ describe TopicUser do
 
     context 'private messages' do
       it 'should ensure recepients and senders are watching' do
-        ActiveRecord::Base.observers.enable :all
 
         target_user = Fabricate(:user)
         post = create_post(archetype: Archetype.private_message, target_usernames: target_user.username);

spec/models/user_action_spec.rb

@@ -3,7 +3,6 @@ require 'rails_helper'
 describe UserAction do
 
   before do
-    ActiveRecord::Base.observers.enable :all
     UserActionCreator.enable
   end
 
@@ -51,6 +50,8 @@ describe UserAction do
     end
 
     it 'includes the events correctly' do
+      PostActionNotifier.enable
+
       mystats = stats_for_user(user)
       expecting = [UserAction::NEW_TOPIC, UserAction::NEW_PRIVATE_MESSAGE, UserAction::GOT_PRIVATE_MESSAGE, UserAction::BOOKMARK].sort
       expect(mystats).to eq(expecting)

spec/rails_helper.rb

@@ -104,9 +104,7 @@ Spork.prefork do
       #
       # $redis = DiscourseMockRedis.new
       #
-      # disable all observers, enable as needed during specs
-      #
-      ActiveRecord::Base.observers.disable :all
+      PostActionNotifier.disable
       SearchIndexer.disable
       UserActionCreator.disable
       NotificationEmailer.disable

spec/services/post_action_notifier_spec.rb

@@ -1,10 +1,10 @@
 require 'rails_helper'
 require_dependency 'post_destroyer'
 
-describe PostAlertObserver do
+describe PostActionNotifier do
 
   before do
-    ActiveRecord::Base.observers.enable :post_alert_observer
+    PostActionNotifier.enable
   end
 
   let!(:evil_trout) { Fabricate(:evil_trout) }

spec/services/post_alerter_spec.rb

@@ -63,8 +63,7 @@ describe PostAlerter do
 
   context 'edits' do
     it 'notifies correctly on edits' do
-
-      ActiveRecord::Base.observers.enable :all
+      PostActionNotifier.enable
 
       post = Fabricate(:post, raw: 'I love waffles')
 
@@ -89,7 +88,7 @@ describe PostAlerter do
   context 'likes' do
 
     it 'notifies on likes after an undo' do
-      ActiveRecord::Base.observers.enable :all
+      PostActionNotifier.enable
 
       post = Fabricate(:post, raw: 'I love waffles')
 
@@ -101,7 +100,7 @@ describe PostAlerter do
     end
 
     it 'notifies on does not notify when never is selected' do
-      ActiveRecord::Base.observers.enable :all
+      PostActionNotifier.enable
 
       post = Fabricate(:post, raw: 'I love waffles')
 
@@ -110,12 +109,11 @@ describe PostAlerter do
 
       PostAction.act(evil_trout, post, PostActionType.types[:like])
 
-
       expect(Notification.where(post_number: 1, topic_id: post.topic_id).count).to eq(0)
     end
 
     it 'notifies on likes correctly' do
-      ActiveRecord::Base.observers.enable :all
+      PostActionNotifier.enable
 
       post = Fabricate(:post, raw: 'I love waffles')