Duplicate notifications, when replying to and mentioning the same user (#8156)

* Refactor Mentions::CreateAll

* Update app/services/mentions/create_all.rb

Co-authored-by: Vaidehi Joshi <vaidehi.sj@gmail.com>

* Refactor for readability

* Try writing tests for duplicate notifications

* Skip Bullet warning, essentially for #current_user

* Fix duplicate notification, when mentioning comment author

* Improve spec readability

* Refactor specs and fix duplicate notificaation for moderator comments

* Refactor spec

* Remove obsolete code and refactor specs

* Remove obsolete spec

* Update spec/requests/comments_create_spec.rb

Co-authored-by: Vaidehi Joshi <vaidehi.sj@gmail.com>

* Get rid of #json_response

* Remove Bullet skipping

* Change #where -> #exists?

Co-authored-by: Vaidehi Joshi <vaidehi.sj@gmail.com>

app/controllers/comments_controller.rb

@@ -63,11 +63,11 @@ class CommentsController < ApplicationController
       checked_code_of_conduct = params[:checked_code_of_conduct].present? && !current_user.checked_code_of_conduct
       current_user.update(checked_code_of_conduct: true) if checked_code_of_conduct
 
-      Mention.create_all(@comment)
       NotificationSubscription.create(
         user: current_user, notifiable_id: @comment.id, notifiable_type: "Comment", config: "all_comments",
       )
       Notification.send_new_comment_notifications_without_delay(@comment)
+      Mention.create_all(@comment)
 
       if @comment.invalid?
         @comment.destroy
@@ -132,8 +132,8 @@ class CommentsController < ApplicationController
     authorize @comment
 
     if @comment.save
-      Mention.create_all(@comment)
       Notification.send_new_comment_notifications_without_delay(@comment)
+      Mention.create_all(@comment)
 
       render json: { status: "created", path: @comment.path }
     elsif (@comment = Comment.where(body_markdown: @comment.body_markdown,

app/services/mentions/create_all.rb

@@ -56,7 +56,13 @@ module Mentions
       Notification.remove_all(notifiable_ids: mentions.pluck(:id), notifiable_type: "Mention") if mentions.present?
     end
 
+    def user_has_comment_notifications?(user)
+      user.notifications.exists?(notifiable_id: @notifiable.id)
+    end
+
     def create_mention_for(user)
+      return if user_has_comment_notifications?(user)
+
       mention = Mention.create(user_id: user.id, mentionable_id: @notifiable.id, mentionable_type: @notifiable.class.name)
       # mentionable_type = model that created the mention, user = user to be mentioned
       Notification.send_mention_notification(mention)

spec/requests/comments_create_spec.rb

@@ -93,4 +93,75 @@ RSpec.describe "CommentsCreate", type: :request do
       expect(response.parsed_body["error"]).to be_present
     end
   end
+
+  context "when there's already a notification for comment" do
+    around do |example|
+      Sidekiq::Testing.inline!(&example)
+    end
+
+    let(:comment_author) { create(:user) }
+    let(:user_replier) { create(:user) }
+    let(:moderator_replier) { create(:user, :admin) }
+    let(:response_template) do
+      create(:response_template, type_of: "mod_comment",
+                                 content: text_mentioning_comment_author, user_id: nil)
+    end
+    let(:text_mentioning_comment_author) do
+      "Hello, @#{comment_author.username}"
+    end
+
+    it "doesn't create mention notification, when replying as regular user" do
+      comment = comment_on_article
+      reply_and_mention_comment_author(comment)
+
+      expect_no_duplicate_notifications_for_comment_author
+    end
+
+    it "doesn't create mention notification, when replying as moderator" do
+      comment = comment_on_article
+      reply_and_mention_comment_author_as_moderator(comment)
+
+      expect_no_duplicate_notifications_for_comment_author
+    end
+
+    private
+
+    def comment_on_article
+      sign_in comment_author
+      post comments_path, params: comment_params
+      expect_request_to_be_successful
+
+      Comment.first
+    end
+
+    def reply_and_mention_comment_author(comment)
+      sign_in user_replier
+      post comments_path, params: comment_params(
+        parent_id: comment.id,
+        body_markdown: text_mentioning_comment_author,
+      )
+      expect_request_to_be_successful
+    end
+
+    def reply_and_mention_comment_author_as_moderator(comment)
+      allow(SiteConfig).to receive(:mascot_user_id).
+        and_return(moderator_replier.id)
+
+      sign_in moderator_replier
+      post moderator_create_comments_path, params: comment_params(
+        parent_id: comment.id,
+      ).merge(response_template: { id: response_template.id })
+      expect(response).to be_successful
+    end
+
+    def expect_no_duplicate_notifications_for_comment_author
+      expect(Mention.count).to eq 0
+      expect(Notification.where(user: comment_author).count).to eq 1
+    end
+
+    def expect_request_to_be_successful
+      expect(response.parsed_body["error"]).to be_nil
+      expect(response).to be_successful
+    end
+  end
 end