Improve specs and system note service

ee/app/services/ee/system_note_service.rb

@@ -69,8 +69,11 @@ module EE
       create_note(NoteSummary.new(object_epic, nil, user, body, action: action))
     end
 
-    def issue_promoted(noteable, noteable_ref, author)
-      direction = noteable.is_a?(Epic) ? :from : :to
+    def issue_promoted(noteable, noteable_ref, author, direction:)
+      unless [:to, :from].include?(direction)
+        raise ArgumentError, "Invalid direction `#{direction}`"
+      end
+
       project = noteable.project
 
       cross_reference = noteable_ref.to_reference(project || noteable.group)

ee/app/services/epics/issue_promote_service.rb

@@ -33,11 +33,11 @@ module Epics
     end
 
     def add_note_from
-      SystemNoteService.issue_promoted(new_entity, original_entity, current_user)
+      SystemNoteService.issue_promoted(new_entity, original_entity, current_user, direction: :from)
     end
 
     def add_note_to
-      SystemNoteService.issue_promoted(original_entity, new_entity, current_user)
+      SystemNoteService.issue_promoted(original_entity, new_entity, current_user, direction: :to)
     end
   end
 end

ee/spec/services/epics/issue_promote_service_spec.rb

@@ -16,9 +16,7 @@ describe Epics::IssuePromoteService do
 
   subject { described_class.new(issue.project, user) }
 
-  def epic
-    Epic.last
-  end
+  let(:epic) { Epic.last }
 
   describe '#execute' do
     context 'when epics are not enabled' do
@@ -52,7 +50,7 @@ describe Epics::IssuePromoteService do
             other_issue = create(:issue, project: create(:project))
 
             expect { subject.execute(other_issue) }
-            .to raise_error(Epics::IssuePromoteService::PromoteError, /group/)
+              .to raise_error(Epics::IssuePromoteService::PromoteError, /group/)
           end
         end
 
@@ -70,7 +68,7 @@ describe Epics::IssuePromoteService do
           end
 
           it 'copies group labels assigned to the issue' do
-            expect(Epic.last.labels).to eq([label1])
+            expect(epic.labels).to eq([label1])
           end
 
           it 'creates a system note on the issue' do

ee/spec/services/system_note_service_spec.rb

@@ -99,7 +99,7 @@ describe SystemNoteService do
 
     context '.issue_promoted' do
       context 'note on the epic' do
-        subject { described_class.issue_promoted(epic, issue, author) }
+        subject { described_class.issue_promoted(epic, issue, author, direction: :from) }
 
         it_behaves_like 'a system note' do
           let(:action) { 'moved' }
@@ -112,7 +112,7 @@ describe SystemNoteService do
       end
 
       context 'note on the issue' do
-        subject { described_class.issue_promoted(issue, epic, author) }
+        subject { described_class.issue_promoted(issue, epic, author, direction: :to) }
 
         it_behaves_like 'a system note' do
           let(:action) { 'moved' }