The first thing to try is to make sure that everything is getting flushed.
For temporary debugging messages I strongly recommend just using
[Core.Std.eprintf "<message>\n%!"].

On 16 June 2015 at 16:03, Kenneth Adam Miller <kennethadammiller@gmail.com>
wrote:

> I'm having trouble with OCaml Async. I wrote a small server with it, and
> right now I'm trying to unit test that server. Here's my code for the
> server:
>
>
> let _main ()=
>   print_endline "Server running";
>   let handler = print_endline in
>   let socket = Tcp.on_port 5554 in
>   let server = Tcp.Server.create socket (fun addr r w ->
>       (Reader.contents r) >>| handler; (Writer.write w "got it")) in
>   server
>
>
>
> In my unit test code I have:
>
> let test_shutdown test_ctxt = Thread_safe.block_on_async_exn (fun () -> (
>       print_endline "test_shutdown";
>       let server = Server._main () in
>       server >>= fun server ->
>       let where = Tcp.to_host_and_port "127.0.0.1" 5554 in
>       Tcp.connect where >>= fun s ->
>         let socket, r, w = s in
>         ignore (Writer.write w "kill");
>         ignore (Writer.flushed w);
>         (Reader.recv r >>> function
>           | `Ok result ->  print_endline ("writing shutdown to server" ^
> result)
>           | `Eof -> ());
>         return ()
>     )); ()
>
>
>
> I see test_shutdown and Server running, but not sign of "writing shutdown
> to server" or even "got it"; why isn't my server or even any of the
> connection executing?
>