Prevent issues to be promoted twice

Prevent issues to be promoted multiple times which
also prevents multiple epics being created.

ee/app/services/epics/issue_promote_service.rb

@@ -5,15 +5,10 @@ module Epics
     PromoteError = Class.new(StandardError)
 
     def execute(issue)
-      @group = issue.project.group
+      @issue = issue
+      @parent_group = issue.project.group
 
-      unless @group
-        raise PromoteError, 'Cannot promote issue because it does not belong to a group!'
-      end
-
-      unless current_user.can?(:admin_issue, issue) && current_user.can?(:create_epic, @group)
-        raise PromoteError, 'Cannot promote issue due to insufficient permissions!'
-      end
+      validate_promotion!
 
       super
 
@@ -23,6 +18,18 @@ module Epics
 
     private
 
+    attr_reader :issue, :parent_group
+
+    def validate_promotion!
+      raise PromoteError, _('Cannot promote issue because it does not belong to a group.') if parent_group.nil?
+      raise PromoteError, _('Cannot promote issue due to insufficient permissions.') unless can_promote?
+      raise PromoteError, _('Issue already promoted to epic.') if issue.promoted?
+    end
+
+    def can_promote?
+      current_user.can?(:admin_issue, issue) && current_user.can?(:create_epic, parent_group)
+    end
+
     def track_event
       ::Gitlab::Tracking.event(
         'epics', 'promote', property: 'issue_id', value: original_entity.id
@@ -30,7 +37,7 @@ module Epics
     end
 
     def create_new_entity
-      @new_entity = Epics::CreateService.new(@group, current_user, params).execute
+      @new_entity = Epics::CreateService.new(parent_group, current_user, params).execute
     end
 
     def update_old_entity

ee/changelogs/unreleased/issue_208974_2.yml

+---
+title: Prevent issues from being promoted twice
+merge_request: 27837
+author:
+type: fixed

ee/lib/ee/gitlab/quick_actions/issue_actions.rb

@@ -69,6 +69,7 @@ module EE
           types Issue
           condition do
             quick_action_target.persisted? &&
+              !quick_action_target.promoted? &&
               current_user.can?(:admin_issue, project) &&
               current_user.can?(:create_epic, project.group)
           end

ee/spec/services/ee/notes/quick_actions_service_spec.rb

@@ -393,6 +393,14 @@ describe Notes::QuickActionsService do
           end
         end
 
+        context 'when issue was already promoted' do
+          it 'does not promote issue' do
+            issue.update(promoted_to_epic_id: epic.id)
+
+            expect { execute(note) }.not_to change { Epic.count }
+          end
+        end
+
         context 'when an issue belongs to a project without group' do
           let(:user_project) { create(:project) }
           let(:issue) { create(:issue, project: user_project) }

ee/spec/services/epics/issue_promote_service_spec.rb

@@ -54,7 +54,7 @@ describe Epics::IssuePromoteService do
           end
         end
 
-        context 'when issue is promoted' do
+        context 'when promoting issue' do
           let!(:issue_mentionable_note) { create(:note, noteable: issue, author: user, project: project, note: "note with mention #{user.to_reference}") }
           let!(:issue_note) { create(:note, noteable: issue, author: user, project: project, note: "note without mention") }
 
@@ -104,6 +104,16 @@ describe Epics::IssuePromoteService do
           end
         end
 
+        context 'when issue was already promoted' do
+          it 'raises error' do
+            epic = create(:epic, group: group)
+            issue.update(promoted_to_epic_id: epic.id)
+
+            expect { subject.execute(issue) }
+              .to raise_error(Epics::IssuePromoteService::PromoteError, /already promoted/)
+          end
+        end
+
         context 'when promoted issue has notes' do
           let!(:discussion) { create(:discussion_note_on_issue, noteable: issue, project: issue.project) }
 

locale/gitlab.pot

@@ -3333,6 +3333,12 @@ msgstr ""
 msgid "Cannot modify provider during creation"
 msgstr ""
 
+msgid "Cannot promote issue because it does not belong to a group."
+msgstr ""
+
+msgid "Cannot promote issue due to insufficient permissions."
+msgstr ""
+
 msgid "Cannot refer to a group milestone by an internal id!"
 msgstr ""
 
@@ -11146,6 +11152,9 @@ msgstr ""
 msgid "Issue Boards"
 msgstr ""
 
+msgid "Issue already promoted to epic."
+msgstr ""
+
 msgid "Issue board focus mode"
 msgstr ""