    # File lib/action_controller/assertions/tag_assertions.rb, line 98
          def assert_tag(*opts)
            clean_backtrace do
              opts = opts.size > 1 ? opts.last.merge({ :tag => opts.first.to_s }) : opts.first
              tag = find_tag(opts)
              assert tag, "expected tag, but no tag found matching #{opts.inspect} in:\n#{@response.body.inspect}"
            end
          end