FIX: Do not trigger post alerts for empty posts. (#7138)

app/jobs/regular/post_alert.rb

@@ -5,7 +5,7 @@ module Jobs
 
     def execute(args)
       post = Post.find_by(id: args[:post_id])
-      if post&.topic
+      if post&.topic && post.raw.present?
         opts = args[:options] || {}
         new_record = true == args[:new_record]
         PostAlerter.new(opts).after_save_post(post, new_record)

spec/components/post_creator_spec.rb

@@ -1141,6 +1141,31 @@ describe PostCreator do
       post_creator = PostCreator.new(user, title: '', raw: '')
       expect { post_creator.create! }.to raise_error(ActiveRecord::RecordNotSaved)
     end
+
+    it "does not generate an alert for empty posts" do
+      Jobs.run_immediately!
+
+      user2 = Fabricate(:user)
+      topic = Fabricate(:private_message_topic,
+        topic_allowed_users: [
+          Fabricate.build(:topic_allowed_user, user: user),
+          Fabricate.build(:topic_allowed_user, user: user2)
+        ],
+      )
+      Fabricate(:topic_user,
+        topic: topic,
+        user: user2,
+        notification_level: TopicUser.notification_levels[:watching]
+      )
+
+      expect {
+        PostCreator.create!(user, raw: "", topic_id: topic.id, skip_validations: true)
+      }.to change { user2.notifications.count }.by(0)
+
+      expect {
+        PostCreator.create!(user, raw: "hello world", topic_id: topic.id, skip_validations: true)
+      }.to change { user2.notifications.count }.by(1)
+    end
   end
 
   context 'private message to a user that has disabled private messages' do