System.Net.Security.Tests.HttpsTestServer.StartServer C# (CSharp) Method

        public void StartServer()
        {
            if (_listener != null)
            {
                throw new InvalidOperationException("Cannot restart server.");
            }

            IPAddress address = IPAddress.Loopback;
            _listener = new TcpListener(address, _port);

            _listener.Start(1);

            _log.WriteLine("[Server] waiting for connections ({0}:{1})", address, _port);
            _port = ((IPEndPoint)_listener.LocalEndpoint).Port;
        }

        public async Task HttpClient_ClientUsesAuxRecord_Ok()
        {
            X509Certificate2 serverCert = Configuration.Certificates.GetServerCertificate();

            var server = new HttpsTestServer(serverCert);
            server.StartServer();
            int port = server.Port;

            string requestString = "https://localhost:" + port.ToString();
            
            using (var handler = new HttpClientHandler() { ServerCertificateCustomValidationCallback = LoopbackServer.AllowAllCertificates })
            using (var client = new HttpClient(handler))
            {
                var tasks = new Task[2];
                tasks[0] = server.RunTest();
                tasks[1] = client.GetStringAsync(requestString);
            
                await Task.WhenAll(tasks).TimeoutAfter(15 * 1000);
            
                if (server.AuxRecordDetected)
                {
                    _output.WriteLine("Test inconclusive: The Operating system preferred a non-CBC or Null cipher.");
                }
                else
                {
                    Assert.True(server.AuxRecordDetected, "Server reports: Client auxiliary record not detected.");
                }
            }
        }