if tc.limitReadSize < size {
			size = tc.limitReadSize
		}
	}

	clientUp, serverUp := spawnTestSocketPair(t, tc.upNet)
	defer serverUp.Close()
	cleanup, err := startTestSocketPeer(t, clientUp, "w", tc.chunkSize, size)
	if err != nil {
		t.Fatal(err)
	}
	defer cleanup(t)
	clientDown, serverDown := spawnTestSocketPair(t, tc.downNet)
	defer serverDown.Close()

	proto     string
	chunkSize int
}

func (bench sendFileBench) benchSendFile(b *testing.B) {
	fileSize := b.N * bench.chunkSize
	f := createTempFile(b, fileSize)

	client, server := spawnTestSocketPair(b, bench.proto)
	defer server.Close()

	cleanUp, err := startTestSocketPeer(b, client, "r", bench.chunkSize, fileSize)
	if err != nil {
		client.Close()
		b.Fatal(err)
	}
	defer cleanUp(b)

		if perr := parseReadError(err); perr != nil {
			ch <- perr
		}
		ch <- err
		return
	}
	if n != len(wb) {
		ch <- fmt.Errorf("read %d; want %d", n, len(wb))
	}
}

func spawnTestSocketPair(t testing.TB, net string) (client, server Conn) {
	t.Helper()

	ln := newLocalListener(t, net)
	defer ln.Close()
	var cerr, serr error
	acceptDone := make(chan struct{})
	go func() {