issuable_base_service.rb

class IssuableBaseService < BaseService
  private

  def create_assignee_note(issuable)
    SystemNoteService.change_assignee(
      issuable, issuable.project, current_user, issuable.assignee)
  end

  def create_milestone_note(issuable)
    SystemNoteService.change_milestone(
      issuable, issuable.project, current_user, issuable.milestone)
  end

  def create_labels_note(issuable, added_labels, removed_labels)
    SystemNoteService.change_label(
      issuable, issuable.project, current_user, added_labels, removed_labels)
  end

  def create_title_change_note(issuable, old_title)
    SystemNoteService.change_title(
      issuable, issuable.project, current_user, old_title)
  end

  def create_branch_change_note(issuable, branch_type, old_branch, new_branch)
    SystemNoteService.change_branch(
      issuable, issuable.project, current_user, branch_type,
      old_branch, new_branch)
  end
end