redmine/db/migrate/099_add_delete_wiki_pages_attachments_permission.rb

class AddDeleteWikiPagesAttachmentsPermission < ActiveRecord::Migration[4.2]
  def self.up
    Role.all.each do |r|
      r.add_permission!(:delete_wiki_pages_attachments) if r.has_permission?(:edit_wiki_pages)
    end
  end

  def self.down
    Role.all.each do |r|
      r.remove_permission!(:delete_wiki_pages_attachments)
    end
  end
end