class Bundler::Thor::Actions::InjectIntoFile

def invoke!
  content = if @behavior == :after
    '\0' + replacement
  else
    replacement + '\0'
  end
  if exists?
    if replace!(/#{flag}/, content, config[:force])
      say_status(:invoke)
    else
      say_status(:unchanged, warning: WARNINGS[:unchanged_no_flag], color: :red)
    end
  else
    unless pretend?
      raise Bundler::Thor::Error, "The file #{ destination } does not appear to exist"
    end
  end
end