public void ReceivesAMessageFrom(string sniperXmppId, Constraint constraint, string message)
{
Message msg;
TimeSpan timeout = 4.Seconds();
Assert.That(messages.TryTake(out msg, timeout), String.Format("did not receive message from sniper within {0} seconds", timeout));
Assert.That(msg.From.User, Is.EqualTo(sniperXmppId), "message was not from {0}", sniperXmppId);
Assert.That(msg.Body, constraint, message);
SniperJid = msg.From;
}