Add widgitised requirement concern for issues

ee/app/models/concerns/issue_widgets/acts_like_requirement.rb

+# frozen_string_literal: true
+
+module IssueWidgets
+  module ActsLikeRequirement
+    extend ActiveSupport::Concern
+
+    included do
+      # This will mean that non-Requirement issues essentially ignore this relationship and always return []
+      has_many :test_reports, -> { joins(:requirement_issue).where(issues: { issue_type: Issue.issue_types[:requirement] }) },
+               foreign_key: :issue_id, inverse_of: :requirement_issue, class_name: 'RequirementsManagement::TestReport'
+    end
+  end
+end

ee/app/models/ee/issue.rb

@@ -18,6 +18,9 @@ module EE
       include IterationEventable
       include HealthStatus
 
+      # widget supporting custom issue types - see https://gitlab.com/gitlab-org/gitlab/-/issues/292035
+      include IssueWidgets::ActsLikeRequirement
+
       scope :order_blocking_issues_desc, -> { reorder(blocking_issues_count: :desc) }
       scope :order_weight_desc, -> { reorder ::Gitlab::Database.nulls_last_order('weight', 'DESC') }
       scope :order_weight_asc, -> { reorder ::Gitlab::Database.nulls_last_order('weight') }

ee/app/models/requirements_management/test_report.rb

@@ -74,7 +74,7 @@ module RequirementsManagement
     end
 
     def only_requirement_type_issue
-      errors.add(:requirement_issue, 'must be an issue of type `Requirement`') if requirement_issue && !requirement_issue.requirement?
+      errors.add(:requirement_issue, "must be a `requirement`. You cannot associate a Test Report with a #{requirement_issue.issue_type}.") if requirement_issue && !requirement_issue.requirement? && will_save_change_to_issue_id?
     end
   end
 end

ee/spec/models/issue_spec.rb

@@ -14,6 +14,28 @@ RSpec.describe Issue do
     it { is_expected.to have_many(:resource_iteration_events) }
     it { is_expected.to have_one(:issuable_sla) }
     it { is_expected.to have_many(:metric_images) }
+
+    it { is_expected.to have_many(:test_reports) }
+
+    context 'for an issue with associated test report' do
+      let_it_be(:requirement_issue) do
+        ri = create(:requirement_issue)
+        create(:test_report, requirement_issue: ri, requirement: nil)
+        ri
+      end
+
+      context 'for an issue of type Requirement' do
+        specify { expect(requirement_issue.test_reports.count).to eq(1) }
+      end
+
+      context 'for an issue of a different type' do
+        before do
+          requirement_issue.update_attribute(:issue_type, :incident)
+        end
+
+        specify { expect(requirement_issue.test_reports.count).to eq(0) }
+      end
+    end
   end
 
   describe 'modules' do

ee/spec/models/requirements_management/test_report_spec.rb

@@ -60,13 +60,31 @@ RSpec.describe RequirementsManagement::TestReport do
           specify { expect(subject).to be_valid }
         end
 
-        context 'when requirement issue is non-requirement issue' do
-          let(:invalid_issue) { build(:issue) }
+        context 'when requirement issue is not of requirement type' do
+          let(:invalid_issue) { create(:issue) }
           let(:requirement_issue_arg) { invalid_issue }
 
           specify do
             expect(subject).not_to be_valid
-            expect(subject.errors.messages[:requirement_issue]).to include(/must be an issue of type `Requirement`/)
+            expect(subject.errors.messages[:requirement_issue]).to include(/You cannot associate a Test Report with a issue/)
+          end
+
+          context 'when requirement issue is invalid but the type field is not dirty' do
+            let(:requirement_arg) { nil }
+            let(:requirement_issue_arg) { requirement_issue }
+
+            before do
+              subject.save!
+
+              # simulate the issue type changing in the background, which will be allowed
+              # the state is technically "invalid" (there are test reports associated with a non-requirement issue)
+              # but we don't want to prevent updating other fields
+              requirement_issue.update_attribute(:issue_type, :incident)
+            end
+
+            specify do
+              expect(subject).to be_valid
+            end
           end
         end
       end

spec/lib/gitlab/import_export/all_models.yml

@@ -54,6 +54,7 @@ issues:
 - namespace
 - note_authors
 - issue_email_participants
+- test_reports
 events:
 - author
 - project