Messaging

public class MessagingTests
{
    const int testPort = 4321;
    const int testCommand = 5;
    const int testReply = 6;

    static readonly IPAddress localhost = IPAddress.Parse("127.0.0.1");

    [Fact]
    public async Task ClientServer()
    {
        using (var server = new TestServer(new IPEndPoint(localhost, testPort)))
        using (var client = new MessageClient(localhost, testPort, 5, 0) { CommandTimeout = 200 })
        {
            await server.Start();
            var tasks = new List<Task>();
            for (var i = 0; i < 1000; i++)
            {
                var b = (byte)(i % 250);
                tasks.Add(Task.Run(async () =>
                {
                    var data = new byte[] { b, ++b, ++b, ++b };
                    var reply = await client.SendMessage(testCommand, data);
                    if (reply.cmd != testReply) throw new Exception("Unexpected reply.");
                    if (reply.data == null || reply.data.Length != data.Length) throw new Exception("Unexpected data length.");
                    for (var iData = 0; iData < data.Length; iData++)
                    {
                        if (reply.data[iData] != data[iData]) throw new Exception("Unexpected data.");
                    }
                }));
            }
            await Task.WhenAll(tasks);
        }
    }

    class TestServer : MessageServer
    {
        public TestServer(IPEndPoint bind) : base(bind)
        {
        }

        protected override Task OnMessage(MessageConnection connection, Message message)
        {
            if (message.cmd != testCommand) throw new Exception("Unexpected command.");
            // Echo back data
            connection.SendResponse(message.id, testReply, message.data);
            return Task.CompletedTask;
        }
    }
}