cst := newClientServerTest(t, mode, HandlerFunc(func(res ResponseWriter, req *Request) {
			_, err := io.Copy(io.Discard, req.Body)
			if !errors.Is(err, os.ErrDeadlineExceeded) {
				t.Errorf("server timed out reading request body: got err %v; want os.ErrDeadlineExceeded", err)
			}
			res.Write([]byte(respBody))
		}), func(ts *httptest.Server) {
			ts.Config.ReadHeaderTimeout = -1 // don't time out while reading headers