    # File lib/rack/mock.rb, line 180
        def body
          # FIXME: apparently users of MockResponse expect the return value of
          # MockResponse#body to be a string.  However, the real response object
          # returns the body as a list.
          #
          # See spec_showstatus.rb:
          #
          #   should "not replace existing messages" do
          #     ...
          #     res.body.should == "foo!"
          #   end
          super.join
        end