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app/mailers/notify.rb

@@ -88,7 +88,7 @@ class Notify < BaseMailer
     # Return group-specific email address if present, otherwise return global
     # email address
-    group_notification_email.presence || @current_user.notification_email
+    group_notification_email || @current_user.notification_email
   end
   # Formats arguments into a String suitable for use as an email subject

doc/workflow/notifications.md

@@ -23,7 +23,7 @@ Each of these settings have levels of notification:
 - Disabled: Turns off notifications.
 - Custom: Receive notifications for custom selected events.
-> Introduced in GitLab 11.9
+> Introduced in GitLab 12.0
 You can also select an email address to receive notifications for each group you belong to.

spec/support/shared_examples/notify_shared_examples.rb

@@ -60,10 +60,9 @@ shared_examples 'an email sent to a user' do
     end
   end
-  context 'when project is in a sub-group' do
+  context 'when project is in a sub-group', :nested_groups do
     before do
-      project.group = subgroup
-      project.save!
+      project.update!(group: subgroup)
     end
     it 'is sent to user\'s subgroup notification email address when set' do