pub(crate) fn construct_socketpair() -> io::Result<(SocketpairStream, SocketpairStream)> {

    #[cfg(not(windows))]

    {

        socketpair::socketpair_stream()

    }

    #[cfg(windows)]

    {

        // Alas, we can't use the socketpair crate on Windows!  It creates a Windows

        // "named pipe".  Windows "named pipe"s are not named pipes.  They are strange

        // things which a bit like an unholy cross between a Unix named pipe (aka a FIFO)

        // and an AF_UNIX socket.  This makes them bizarre and awkward.  They are best

        // avoided if possible.

        //

        // We have to use this nonsense instead.  It will cause these tests to fail on

        // some absurdly restrictive windows firewalls; that's a price we can afford.

        //

        // For details see

        // https://gitlab.torproject.org/tpo/core/arti/-/merge_requests/2758#note_3155460

        let listener = std::net::TcpListener::bind("127.0.0.1:0")?;

        let addr = listener.local_addr()?;

        let s1 = std::net::TcpStream::connect(addr)?;

        let (s2, s2_addr) = listener.accept()?;

        assert_eq!(s1.local_addr().unwrap(), s2_addr);

        Ok((s1, s2))

    }

}