Fallback to using schedule in text

- Rename method to notify_via_escalation

ee/app/models/incident_management/pending_escalations/alert.rb

@@ -28,7 +28,7 @@ module IncidentManagement
       validates :rule_id, presence: true, uniqueness: { scope: [:alert_id] }
 
       delegate :project, to: :alert
-      delegate :policy, to: :rule
+      delegate :policy, to: :rule, allow_nil: true
     end
   end
 end

ee/app/services/ee/system_note_service.rb

@@ -112,8 +112,8 @@ module EE
       issuables_service(noteable, project, author).publish_issue_to_status_page
     end
 
-    def alert_via_escalation(noteable, project, recipients, escalation_policy)
-      escalations_service(noteable, project).alert_via_escalation(recipients, escalation_policy)
+    def notify_via_escalation(noteable, project, recipients, escalation_policy, oncall_schedule)
+      escalations_service(noteable, project).notify_via_escalation(recipients, escalation_policy, oncall_schedule)
     end
 
     private

ee/app/services/incident_management/pending_escalations/process_service.rb

@@ -49,7 +49,7 @@ module IncidentManagement
       end
 
       def create_system_notes
-        SystemNoteService.alert_via_escalation(target, project, oncall_notification_recipients, escalation.policy)
+        SystemNoteService.notify_via_escalation(target, project, oncall_notification_recipients, escalation.policy, oncall_schedule)
       end
 
       def oncall_notification_recipients

ee/app/services/system_notes/escalations_service.rb

@@ -8,8 +8,12 @@ module SystemNotes
       @author = User.alert_bot
     end
 
-    def alert_via_escalation(recipients, escalation_policy)
-      body = "notified #{recipients.map(&:to_reference).to_sentence} of this alert via escalation policy **#{escalation_policy.name}**"
+    def notify_via_escalation(recipients, escalation_policy, oncall_schedule)
+      body = if escalation_policy
+               "notified #{recipients.map(&:to_reference).to_sentence} of this alert via escalation policy **#{escalation_policy.name}**"
+             else
+               "notified #{recipients.map(&:to_reference).to_sentence} of this alert via schedule **#{oncall_schedule.name}**, per an escalation rule which no longer exists"
+             end
 
       create_note(NoteSummary.new(noteable, project, author, body, action: 'new_alert_added'))
     end

ee/spec/models/incident_management/pending_escalations/alert_spec.rb

@@ -11,6 +11,7 @@ RSpec.describe IncidentManagement::PendingEscalations::Alert do
     it { is_expected.to validate_presence_of(:process_at) }
     it { is_expected.to validate_presence_of(:status) }
     it { is_expected.to delegate_method(:project).to(:alert) }
+    it { is_expected.to delegate_method(:policy).to(:rule).allow_nil }
     it { is_expected.to validate_uniqueness_of(:rule_id).scoped_to([:alert_id]) }
   end
 

ee/spec/services/incident_management/pending_escalations/process_service_spec.rb

@@ -51,7 +51,7 @@ RSpec.describe IncidentManagement::PendingEscalations::ProcessService do
 
       it 'creates a system note' do
         expect(SystemNoteService)
-          .to receive(:alert_via_escalation).with(alert, project, [a_kind_of(User)], escalation_policy)
+          .to receive(:notify_via_escalation).with(alert, project, [a_kind_of(User)], escalation_policy, schedule_1)
           .and_call_original
 
         expect { execute }.to change(Note, :count).by(1)

ee/spec/services/system_notes/escalations_service_spec.rb

@@ -8,10 +8,11 @@ RSpec.describe SystemNotes::EscalationsService do
   let_it_be(:user_2) { create(:user) }
   let_it_be(:author) { User.alert_bot }
 
-  describe '#alert_via_escalation' do
-    subject { described_class.new(noteable: noteable, project: project).alert_via_escalation([user, user_2], escalation_policy) }
+  describe '#notify_via_escalation' do
+    subject { described_class.new(noteable: noteable, project: project).notify_via_escalation([user, user_2], escalation_policy, oncall_schedule) }
 
     let_it_be(:escalation_policy) { create(:incident_management_escalation_policy, project: project) }
+    let_it_be(:oncall_schedule) { create(:incident_management_oncall_schedule, project: project) }
     let_it_be(:noteable) { create(:alert_management_alert, project: project) }
 
     it_behaves_like 'a system note' do
@@ -21,5 +22,13 @@ RSpec.describe SystemNotes::EscalationsService do
     it 'posts the correct text to the system note' do
       expect(subject.note).to match("notified #{user.to_reference} and #{user_2.to_reference} of this alert via escalation policy **#{escalation_policy.name}**")
     end
+
+    context 'when policy is missing' do
+      let_it_be(:escalation_policy) { nil }
+
+      it 'posts the correct text to the system note' do
+        expect(subject.note).to match("notified #{user.to_reference} and #{user_2.to_reference} of this alert via schedule **#{oncall_schedule.name}**, per an escalation rule which no longer exists")
+      end
+    end
   end
 end