class RuboCop::Cop::Rails::MailerName

def autocorrect(corrector, node)
  if node.casgn_type?
    name = node.children[1]
    corrector.replace(node.loc.name, "#{name}Mailer")
  else
    name = node.children.last
    corrector.replace(node, "#{name}Mailer")
  end
end