Add IID to a generic alert issue title

https://gitlab.com/gitlab-org/gitlab/issues/34687

ee/app/models/ee/issue.rb

@@ -33,6 +33,8 @@ module EE
       has_many :prometheus_alerts, through: :prometheus_alert_events
 
       validates :weight, allow_nil: true, numericality: { greater_than_or_equal_to: 0 }
+
+      after_create :update_generic_alert_issue_if_applicable
     end
 
     class_methods do
@@ -129,5 +131,26 @@ module EE
         [WEIGHT_NONE] + WEIGHT_RANGE.to_a
       end
     end
+
+    private
+
+    def update_generic_alert_issue_if_applicable
+      return unless has_default_generic_alert_title? && alerts_service_activated?
+
+      update_column(:title, "#{title} #{id}")
+    end
+
+    def has_default_generic_alert_title?
+      title == ::Gitlab::Alerting::NotificationPayloadParser::DEFAULT_TITLE
+    end
+
+    def incident_management_available?
+      project.feature_available?(:incident_management)
+    end
+
+    def alerts_service_activated?
+      incident_management_available? &&
+        project.alerts_service.try(:active?)
+    end
   end
 end

ee/spec/models/issue_spec.rb

@@ -7,6 +7,56 @@ describe Issue do
 
   using RSpec::Parameterized::TableSyntax
 
+  context 'callbacks' do
+    describe '.after_create' do
+      set(:project) { create(:project) }
+
+      context 'when issue title is "New: Incident"' do
+        let(:issue) { build(:issue, project: project, title: 'New: Incident') }
+
+        context 'when incident management available' do
+          before do
+            stub_licensed_features(incident_management: true)
+          end
+
+          context 'when alerts service is active' do
+            let!(:alerts_service) { create(:alerts_service, project: project) }
+
+            it 'updates issue title with the IID' do
+              issue.save
+
+              expect(issue.reload.title).to eq("New: Incident #{issue.id}")
+            end
+          end
+
+          context 'when alerts service is not active' do
+            it 'does not change issue title' do
+              expect { issue.save }.not_to change { issue.title }
+            end
+          end
+        end
+
+        context 'when incident management is not available' do
+          before do
+            stub_licensed_features(incident_management: false)
+          end
+
+          it 'does not change issue title' do
+            expect { issue.save }.not_to change { issue.title }
+          end
+        end
+      end
+
+      context 'when issue title is not "New: Incident"' do
+        let(:issue) { build(:issue, project: project, title: 'Not New: Incident') }
+
+        it 'does not change issue title' do
+          expect { issue.save }.not_to change { issue.title }
+        end
+      end
+    end
+  end
+
   context 'scopes' do
     describe '.service_desk' do
       it 'returns the service desk issue' do