[57251] Fix mail_alert_sent not being set correctly on update

https://community.openproject.org/wp/57251

When a notification exists for a work package journal for a reason other
than :mentioned, then its `mail_alert_sent` value is `nil`.

On a subsequent update of the work package which mentions the user, the
existing notification is updated. In this update, the `mail_alert_sent`
value must be changed from `nil` to `false` if the reason is :mentioned.
Without it, the immediate notification email for the mention would not
be sent.

app/services/notifications/create_from_model_service.rb

@@ -129,6 +129,7 @@ def update_notification(recipient_id, reason)
     Notifications::UpdateService
       .new(model: existing_notification, user:, contract_class: EmptyContract)
       .call(read_ian: strategy.supports_ian?(reason) ? false : nil,
+            mail_alert_sent: existing_notification.mail_alert_sent || (strategy.supports_mail?(reason) ? false : nil),
             reason:)
   end
 

spec/services/notifications/create_from_model_service_work_package_spec.rb

@@ -997,7 +997,7 @@
         context "when there is already a notification for the journal (because it was aggregated)" do
           let(:note) { "Hello user:\"#{recipient_login}\"" }
           let!(:existing_notification) do
-            create(:notification, resource:, journal:, recipient:, reason: :mentioned, read_ian: true)
+            create(:notification, resource:, journal:, recipient:, reason: :mentioned, read_ian: true, mail_alert_sent: nil)
           end
 
           it_behaves_like "creates no notification"
@@ -1006,7 +1006,27 @@
             call
 
             expect(existing_notification.reload.read_ian)
-              .to be_falsey
+              .to be(false)
+          end
+
+          it "changes the mail_alert_sent of the existing notification from nil to false" do
+            call
+
+            expect(existing_notification.reload.mail_alert_sent)
+              .to be(false)
+          end
+
+          context "and the mail alert has already been sent" do
+            before do
+              existing_notification.update(mail_alert_sent: true)
+            end
+
+            it "keeps the mail_alert_sent of the existing notification to true" do
+              call
+
+              expect(existing_notification.reload.mail_alert_sent)
+                .to be(true)
+            end
           end
         end