.NET Core send https request through proxy using sockets

HttpTests.cs

using System.IO;
using System.Net;
using System.Net.Security;
using System.Net.Sockets;
using System.Security.Authentication;
using System.Text;
using System.Threading.Tasks;
using Xunit;

namespace Matthew.Lymer.Tests
{
    public sealed class HttpTests
    {
        private static readonly Encoding Utf8NoBom = new UTF8Encoding(false);

        [Fact]
        public async Task ShouldConnectToGoogleOverHttps()
        {
            using (var socket = new Socket(SocketType.Stream, ProtocolType.IP))
            {
                socket.NoDelay = true;
                await socket.ConnectAsync(new DnsEndPoint("localhost", 8888));

                using (var stream = new NetworkStream(socket, true))
                {
                    using (var writer = new StreamWriter(stream, Utf8NoBom, 2048, true))
                    {
                        await writer.WriteAsync("CONNECT google.com:443 HTTP/1.1\r\n");
                        await writer.WriteAsync("Host: google.com:443\r\n");
                        await writer.WriteAsync("Connection: keep-alive\r\n");
                        await writer.WriteAsync("\r\n");
                    }

                    using (var reader = new StreamReader(stream, Utf8NoBom, false, 2048, true))
                    {
                        while (true)
                        {
                            var line = await reader.ReadLineAsync();

                            if (string.IsNullOrEmpty(line))
                            {
                                break;
                            }
                        }
                    }

                    using (var sslStream = new SslStream(stream, true))
                    {
                        await sslStream.AuthenticateAsClientAsync("google.com", null, SslProtocols.Tls11 | SslProtocols.Tls12, true);

                        using (var writer = new StreamWriter(sslStream, Utf8NoBom, 2048, true))
                        {
                            await writer.WriteAsync("GET / HTTP/1.1\r\n");
                            await writer.WriteAsync("Host: google.ca\r\n");
                            await writer.WriteAsync("Connection: close\r\n");
                            await writer.WriteAsync("Accept: */*\r\n");
                            await writer.WriteAsync("\r\n");
                        }

                        using (var reader = new StreamReader(sslStream, Utf8NoBom, false, 2048, true))
                        {
                            var response = await reader.ReadToEndAsync();

                            Assert.Contains("HTTP/1.1 301 Moved Permanently", response);
                        }
                    }
                }
            }
        }
    }
}