def to_real_url(url, test_case = nil, &bl)
      case config.host
      when Proc
        config.host.call(url, test_case)
      when String
        url =~ /^http/ ? url : "#{config.host}#{url}"
      else
        return url if url =~ /^http/
        return yield(url) if block_given?
        raise "Unable to resolve `#{url}` : no host resolver provided\nSee `Configuration#host="
      end
    end
def to_real_url(url, test_case = nil, &bl)
      case config.host
      when Proc
        config.host.call(url, test_case)
      when String
        url =~ /^http/ ? url : "#{config.host}#{url}"
      else
        return url if url =~ /^http/
        return yield(url) if block_given?
        raise "Unable to resolve `#{url}` : no host resolver provided\nSee `Configuration#host="
      end
    end
Convert an instantiated URL found in a webservice definition
 to a real URL, using the configuration host.

 When no host resolved on the configuration and the url is not
 already an absolute URL, yields the block if given, or raise
 an exception.