Update iteration changed notification format

- Iteration period (start and due dates) should be the link/main text
- Iteration title will be made optional and should be wrapped in a
  parenthesis for display.
- Iteration cadence name should be displayed when the FF is turned on.
- Remove project iteration from notification spec.
   Project iteration has been abandoned. Iteration will always be scoped to groups.

Changelog: changed
EE: true

ee/app/models/ee/iteration.rb

@@ -149,6 +149,12 @@ module EE
       end
     end
 
+    def display_text
+      return period unless group.iteration_cadences_feature_flag_enabled?
+
+      "#{iterations_cadence.title} #{period}"
+    end
+
     def state
       STATE_ENUM_MAP.key(state_enum)
     end
@@ -295,5 +301,9 @@ module EE
 
       errors.add(:title, _('already being used for another iteration within this cadence.')) if title_exists
     end
+
+    def period
+      "#{start_date.to_s(:medium)} - #{due_date.to_s(:medium)}"
+    end
   end
 end

ee/app/views/notify/changed_iteration_email.html.haml

 %p
   = _('Iteration changed to')
-  %strong= link_to(@iteration.name, @iteration_url)
-  - if date_range = timebox_date_range(@iteration)
-    = "(#{date_range})"
+  %strong= link_to(@iteration.display_text, @iteration_url)
+  = "(#{@iteration.title})"

ee/app/views/notify/changed_iteration_email.text.erb

-<%= _('Iteration changed to') %> <%= @iteration.name %><% if date_range = timebox_date_range(@iteration) %> (<%= date_range %>)<% end %> ( <%= @iteration_url %> )
+<%= _('Iteration changed to') %> <%= @iteration.display_text %> (<%= @iteration.title %>) ( <%= @iteration_url %> )

ee/spec/mailers/ee/emails/issues_spec.rb

@@ -12,14 +12,31 @@ RSpec.describe Emails::Issues do
   let_it_be(:issue) { create(:issue, project: project) }
 
   context 'iterations' do
-    let_it_be(:iteration) { create(:iteration, group: group) }
+    let_it_be(:iterations_cadence) { create(:iterations_cadence, title: "Plan cadence", group: group) }
+    let_it_be(:iteration) { create(:iteration, iterations_cadence: iterations_cadence, start_date: Date.new(2022, 9, 30), due_date: Date.new(2022, 10, 4)) }
 
-    describe '#changed_iteration_issue_email' do
+    describe '#changed_iteration_issue_email', :aggregate_failures do
       subject { Notify.changed_iteration_issue_email(user.id, issue.id, iteration, user.id) }
 
+      before do
+        stub_feature_flags(iteration_cadences: false)
+      end
+
       it 'shows the iteration it was changed to' do
         expect(subject).to have_body_text 'Iteration changed to'
+        expect(subject).to have_body_text 'Sep 30, 2022 - Oct 4, 2022'
         expect(subject).to have_body_text iteration.name
+        expect(subject).not_to have_body_text 'Plan cadence'
+      end
+
+      context 'when iteration_cadences FF enabled' do
+        before do
+          stub_feature_flags(iteration_cadences: true)
+        end
+
+        it 'shows the iteration it was changed to' do
+          expect(subject).to have_body_text 'Plan cadence Sep 30, 2022 - Oct 4, 2022'
+        end
       end
     end
 

ee/spec/models/ee/iteration_spec.rb

@@ -40,6 +40,28 @@ RSpec.describe Iteration do
     end
   end
 
+  describe '#display_text' do
+    let_it_be(:group) { create(:group) }
+    let_it_be(:iterations_cadence) { create(:iterations_cadence, title: "Plan cadence", group: group) }
+    let_it_be(:iteration) { create(:iteration, iterations_cadence: iterations_cadence, start_date: Date.new(2022, 9, 30), due_date: Date.new(2022, 10, 4)) }
+
+    subject { iteration.display_text }
+
+    before do
+      stub_feature_flags(iteration_cadences: false)
+    end
+
+    it { is_expected.to eq('Sep 30, 2022 - Oct 4, 2022') }
+
+    context 'when iteration_cadences FF enabled' do
+      before do
+        stub_feature_flags(iteration_cadences: true)
+      end
+
+      it { is_expected.to eq('Plan cadence Sep 30, 2022 - Oct 4, 2022') }
+    end
+  end
+
   describe '.reference_pattern' do
     let_it_be(:group) { create(:group) }
     let_it_be(:iteration_cadence) { create(:iterations_cadence, group: group) }

ee/spec/services/ee/notification_service_spec.rb

@@ -441,7 +441,7 @@ RSpec.describe EE::NotificationService, :mailer do
         let(:guest) { create(:user) }
         let(:admin) { create(:admin) }
         let(:confidential_issue) { create(:issue, :confidential, project: project, title: 'Confidential issue', author: author, assignees: [assignee]) }
-        let(:iteration) { create(:iteration, :skip_project_validation, project: project, issues: [confidential_issue]) }
+        let(:iteration) { create(:iteration, :skip_project_validation, group: group, issues: [confidential_issue]) }
 
         it "emails subscribers of the issue's iteration that can read the issue" do
           project.add_developer(member)
@@ -472,7 +472,7 @@ RSpec.describe EE::NotificationService, :mailer do
       let(:mailer_method) { :changed_iteration_issue_email }
 
       context do
-        let(:new_iteration) { create(:iteration, :skip_project_validation, project: project, issues: [issue]) }
+        let(:new_iteration) { create(:iteration, :skip_project_validation, group: group, issues: [issue]) }
         let!(:subscriber_to_new_iteration) { create(:user) { |u| issue.toggle_subscription(u, project) } }
 
         it_behaves_like 'altered iteration notification on issue' do
@@ -495,7 +495,7 @@ RSpec.describe EE::NotificationService, :mailer do
         let(:guest) { create(:user) }
         let(:admin) { create(:admin) }
         let(:confidential_issue) { create(:issue, :confidential, project: project, title: 'Confidential issue', author: author, assignees: [assignee]) }
-        let(:new_iteration) { create(:iteration, :skip_project_validation, project: project, issues: [confidential_issue]) }
+        let(:new_iteration) { create(:iteration, :skip_project_validation, group: group, issues: [confidential_issue]) }
 
         it "emails subscribers of the issue's iteration that can read the issue" do
           project.add_developer(member)