Bugfix promoting an Issue with attachments to Epic

https://gitlab.com/gitlab-org/gitlab/-/merge_requests/38646 had
introduced a bug where `MarkdownContentRewriter` was passed the target's
`#project`. For Epics, this can be `nil`. Instead, we need to pass the
target's `#resource_parent`, which for an Epic, will be a Group.

https://gitlab.com/gitlab-org/gitlab/-/issues/236190

app/services/issuable/clone/base_service.rb

@@ -44,7 +44,7 @@ module Issuable
           current_user,
           original_entity.description,
           original_entity.project,
-          new_entity.project
+          new_parent
         ).execute
 
         new_entity.update!(description: rewritten_description)
@@ -69,7 +69,7 @@ module Issuable
       end
 
       def new_parent
-        new_entity.project || new_entity.group
+        new_entity.resource_parent
       end
 
       def group

app/services/markdown_content_rewriter_service.rb

@@ -7,6 +7,10 @@ class MarkdownContentRewriterService
   REWRITERS = [Gitlab::Gfm::ReferenceRewriter, Gitlab::Gfm::UploadsRewriter].freeze
 
   def initialize(current_user, content, source_parent, target_parent)
+    # See https://gitlab.com/gitlab-org/gitlab/-/merge_requests/39654#note_399095117
+    raise ArgumentError, 'The rewriter classes require that `source_parent` is a `Project`' \
+      unless source_parent.is_a?(Project)
+
     @current_user = current_user
     @content = content.presence
     @source_parent = source_parent

app/services/notes/copy_service.rb

@@ -13,7 +13,6 @@ module Notes
       @from_noteable = from_noteable
       @to_noteable = to_noteable
       @from_project = from_noteable.project
-      @to_project = to_noteable.project
       @new_discussion_ids = {}
     end
 
@@ -27,8 +26,7 @@ module Notes
 
     private
 
-    attr_reader :from_noteable, :to_noteable, :from_project, :to_project,
-                :current_user, :new_discussion_ids
+    attr_reader :from_noteable, :to_noteable, :from_project, :current_user, :new_discussion_ids
 
     def copy_note(note)
       new_note = note.dup
@@ -40,7 +38,7 @@ module Notes
 
     def params_from_note(note, new_note)
       new_discussion_ids[note.discussion_id] ||= Discussion.discussion_id(new_note)
-      rewritten_note = MarkdownContentRewriterService.new(current_user, note.note, from_project, to_project).execute
+      rewritten_note = MarkdownContentRewriterService.new(current_user, note.note, from_project, to_noteable.resource_parent).execute
 
       new_params = {
         project: to_noteable.project,

changelogs/unreleased/236190-bugfix-issue-promote-with-attachments.yml

+---
+title: Fix bug when promoting an Issue with attachments to an Epic
+merge_request: 39654
+author:
+type: fixed

ee/spec/services/epics/issue_promote_service_spec.rb

@@ -103,6 +103,18 @@ RSpec.describe Epics::IssuePromoteService do
               expect(epic.user_mentions.count).to eq 2
             end
           end
+
+          context 'when issue description has an attachment' do
+            let(:image_uploader) { build(:file_uploader, project: project) }
+            let(:description) { "A description and image: #{image_uploader.markdown_link}" }
+
+            it 'copies the description, rewriting the attachment' do
+              new_image_uploader = Upload.last.retrieve_uploader
+
+              expect(new_image_uploader.markdown_link).not_to eq(image_uploader.markdown_link)
+              expect(epic.description).to eq("A description and image: #{new_image_uploader.markdown_link}")
+            end
+          end
         end
 
         context 'when an issue belongs to an epic' do
@@ -130,20 +142,28 @@ RSpec.describe Epics::IssuePromoteService do
           end
         end
 
-        context 'when promoted issue has notes' do
-          let!(:discussion) { create(:discussion_note_on_issue, noteable: issue, project: issue.project) }
-
+        context 'when issue has notes' do
           before do
             allow(Gitlab::Tracking).to receive(:event).with('epics', 'promote', an_instance_of(Hash))
             issue.reload
           end
 
-          it 'creates a new epic with all notes' do
+          it 'copies all notes' do
+            discussion = create(:discussion_note_on_issue, noteable: issue, project: issue.project)
+
             epic = subject.execute(issue)
             expect(epic.notes.count).to eq(issue.notes.count)
             expect(epic.notes.where(discussion_id: discussion.discussion_id).count).to eq(0)
             expect(issue.notes.where(discussion_id: discussion.discussion_id).count).to eq(1)
           end
+
+          it 'copies note attachments' do
+            create(:discussion_note_on_issue, :with_attachment, noteable: issue, project: issue.project)
+
+            epic = subject.execute(issue)
+
+            expect(epic.notes.user.first.attachment).to be_kind_of(AttachmentUploader)
+          end
         end
       end
     end

spec/services/markdown_content_rewriter_service_spec.rb

@@ -3,12 +3,20 @@
 require 'spec_helper'
 
 RSpec.describe MarkdownContentRewriterService do
-  describe '#execute' do
-    let_it_be(:user) { create(:user) }
-    let_it_be(:source_parent) { create(:project, :public) }
-    let_it_be(:target_parent) { create(:project, :public) }
-    let(:content) { 'My content' }
+  let_it_be(:user) { create(:user) }
+  let_it_be(:source_parent) { create(:project, :public) }
+  let_it_be(:target_parent) { create(:project, :public) }
+  let(:content) { 'My content' }
+
+  describe '#initialize' do
+    it 'raises an error if source_parent is not a Project' do
+      expect do
+        described_class.new(user, content, create(:group), target_parent)
+      end.to raise_error(ArgumentError, 'The rewriter classes require that `source_parent` is a `Project`')
+    end
+  end
 
+  describe '#execute' do
     subject { described_class.new(user, content, source_parent, target_parent).execute }
 
     it 'calls the rewriter classes successfully', :aggregate_failures do