Allow people to subscribe to mentions in updated MRs and Issues

This slightly changes the semantics of the 'New Issue' and 'New MR' events to
include new mentions in edited Mentionables.

An alternative would be to introduce 'Issue updated' and 'MR updated' events,
but that would lead to questions about why those events were only available
to new mentions, and not existing mentions as well, so hold off for now.

app/services/notification_service.rb

@@ -500,7 +500,8 @@ class NotificationService
   end
 
   def new_mentions_in_resource_email(target, project, new_mentioned_users, current_user, method)
-    recipients = build_recipients(target, project, current_user) & new_mentioned_users
+    recipients = build_recipients(target, project, current_user, action: "new")
+    recipients = recipients & new_mentioned_users
 
     recipients.each do |recipient|
       mailer.send(method, recipient.id, target.id, current_user.id).deliver_later

doc/workflow/notifications.md

@@ -67,7 +67,7 @@ In all of the below cases, the notification will be sent to:
 - Participants:
   - the author and assignee of the issue/merge request
   - authors of comments on the issue/merge request
-  - anyone mentioned by `@username` in the issue/merge request description
+  - anyone mentioned by `@username` in the issue/merge request title or description
   - anyone mentioned by `@username` in any of the comments on the issue/merge request
 
     ...with notification level "Participating" or higher
@@ -89,6 +89,11 @@ In all of the below cases, the notification will be sent to:
 | Merge merge request    | |
 | New comment            | The above, plus anyone mentioned by `@username` in the comment, with notification level "Mention" or higher |
 
+
+In addition, if the title or description of an Issue or Merge Request is
+changed, notifications will be sent to any **new** mentions by `@username` as
+if they had been mentioned in the original text.
+
 You won't receive notifications for Issues, Merge Requests or Milestones
 created by yourself. You will only receive automatic notifications when
 somebody else comments or adds changes to the ones that you've created or

spec/services/notification_service_spec.rb

@@ -411,12 +411,13 @@ describe NotificationService, services: true do
       end
 
       it "should email new mentions with a watch level higher than participant" do
-        send_notifications(@u_watcher, @u_participant_mentioned)
+        send_notifications(@u_watcher, @u_participant_mentioned, @u_custom_global)
 
         should_email(@u_watcher)
         should_email(@u_participant_mentioned)
+        should_email(@u_custom_global)
 
-        expect(ActionMailer::Base.deliveries.count).to eq 2
+        expect(ActionMailer::Base.deliveries.count).to eq 3
       end
 
       it "should not email new mentions with a watch level equal to or less than participant" do
@@ -726,6 +727,8 @@ describe NotificationService, services: true do
     before do
       build_team(merge_request.target_project)
       add_users_with_subscription(merge_request.target_project, merge_request)
+      update_custom_notification(:new_merge_request, @u_guest_custom, project)
+      update_custom_notification(:new_merge_request, @u_custom_global)
       ActionMailer::Base.deliveries.clear
     end
 
@@ -801,12 +804,13 @@ describe NotificationService, services: true do
       end
 
       it "should email new mentions with a watch level higher than participant" do
-        send_notifications(@u_watcher, @u_participant_mentioned)
+        send_notifications(@u_watcher, @u_participant_mentioned, @u_custom_global)
 
         should_email(@u_watcher)
         should_email(@u_participant_mentioned)
+        should_email(@u_custom_global)
 
-        expect(ActionMailer::Base.deliveries.count).to eq 2
+        expect(ActionMailer::Base.deliveries.count).to eq 3
       end
 
       it "should not email new mentions with a watch level equal to or less than participant" do