DEV: Leaking state in `PostActionNotifier` in tests take 2.

Follow-up to a3b48826

app/services/post_action_notifier.rb

@@ -4,13 +4,17 @@ class PostActionNotifier
 
   def self.disable
     @disabled = true
-    @custom_post_revision_notifier_recipients = nil
   end
 
   def self.enable
     @disabled = false
   end
 
+  # For testing purposes
+  def self.reset!
+    @custom_post_revision_notifier_recipients = nil
+  end
+
   def self.alerter
     @alerter ||= PostAlerter.new
   end

spec/services/post_action_notifier_spec.rb

@@ -108,6 +108,10 @@ describe PostActionNotifier do
         end
       end
 
+      after do
+        PostActionNotifier.reset!
+      end
+
       it 'notifies the specified user of the revision' do
         expect {
           post.revise(evil_trout, raw: "world is the new body of the message")