Prevent error when promoting issues to epics

Do not clone specific foreign_keys when promoting issue to epic.
Prevents database constraint error from  happening.

app/services/issuable/clone/attributes_rewriter.rb

@@ -73,12 +73,17 @@ module Issuable
 
         copy_events(ResourceStateEvent.table_name, original_entity.resource_state_events) do |event|
           event.attributes
-            .except('id')
+            .except(*blocked_state_event_attributes)
             .merge(entity_key => new_entity.id,
                    'state' => ResourceStateEvent.states[event.state])
         end
       end
 
+      # Overriden on EE::Issuable::Clone::AttributesRewriter
+      def blocked_state_event_attributes
+        ['id']
+      end
+
       def event_attributes_with_milestone(event, milestone)
         event.attributes
           .except('id')

ee/app/services/ee/issuable/clone/attributes_rewriter.rb

@@ -15,6 +15,11 @@ module EE
 
         private
 
+        override :blocked_state_event_attributes
+        def blocked_state_event_attributes
+          super.push('issue_id')
+        end
+
         def copy_resource_weight_events
           return unless both_respond_to?(:resource_weight_events)
 

ee/changelogs/unreleased/issue_296567.yml

+---
+title: Prevent errors when promoting issues to epics
+merge_request: 60860
+author:
+type: fixed

ee/spec/services/ee/issuable/clone/attributes_rewriter_spec.rb

@@ -40,6 +40,24 @@ RSpec.describe Issuable::Clone::AttributesRewriter do
         end
       end
 
+      context 'when cloning state events' do
+        before do
+          create(:resource_state_event, issue: original_issue)
+        end
+
+        it 'ignores issue_id attribute' do
+          milestone = create(:milestone, title: 'milestone', group: group)
+          original_issue.update(milestone: milestone)
+
+          subject.execute
+
+          latest_state_event = ResourceStateEvent.last
+          expect(latest_state_event).to be_valid
+          expect(latest_state_event.issue_id).to be_nil
+          expect(latest_state_event.epic).to eq(new_epic)
+        end
+      end
+
       context 'when issue has weight events' do
         it 'ignores copying weight events' do
           create_list(:resource_weight_event, 2, issue: original_issue)

ee/spec/services/epics/issue_promote_service_spec.rb

@@ -130,6 +130,25 @@ RSpec.describe Epics::IssuePromoteService, :aggregate_failures do
           end
         end
 
+        context 'when issue has resource state event' do
+          let!(:issue_event) { create(:resource_state_event, issue: issue) }
+
+          it 'does not raise error' do
+            expect { subject.execute(issue) }.not_to raise_error
+          end
+
+          it 'promotes issue successfully' do
+            epic = subject.execute(issue)
+
+            resource_state_event = epic.resource_state_events.first
+            expect(epic.title).to eq(issue.title)
+            expect(issue.promoted_to_epic).to eq(epic)
+            expect(resource_state_event.issue_id).to eq(nil)
+            expect(resource_state_event.epic_id).to eq(epic.id)
+            expect(resource_state_event.state).to eq(issue_event.state)
+          end
+        end
+
         context 'when promoting issue to a different group' do
           it 'creates a new epic with correct attributes' do
             epic = subject.execute(issue, new_group)