Spike downloading files from behind login with Coypu

RestrictedFilesSpike.cs

using System;
using System.IO;
using System.Net;
using Coypu;
using OpenQA.Selenium.Remote;

namespace Itv.BB.Bloom.Web.CMSSite.AcceptanceTests.Migration.Support
{
  public static class CoypuExtensions 
  {
    public static void DownloadFile(this Session browser, string url, string saveAs) {
        DownloadFile(browser, url,
                        reader =>
                        {
                            const int bufferSize = 1024;
                            using (var fileStream = File.Create(saveAs)) {
                                var buffer = new byte[0];
                                while (fileStream.Position == 0 || buffer.Length > 0) {
                                    buffer = reader.ReadBytes(bufferSize);
                                    fileStream.Write(buffer, 0, buffer.Length);
                                }
                            }
                        });
    }

    public static void DownloadFile(this Session browser, string url, Action<BinaryReader> readResponseStream) {
        var httpWebRequest = (HttpWebRequest)WebRequest.Create(new Uri(url));
        httpWebRequest.CookieContainer = new CookieContainer();

        var cookies = ((RemoteWebDriver)browser.Native).Manage().Cookies.AllCookies;
        foreach (var cookie in cookies) {
            httpWebRequest.CookieContainer.Add(new Cookie(cookie.Name, cookie.Value, cookie.Path, cookie.Domain));
        }

        var webResponse = httpWebRequest.GetResponse();
        using (var reader = new BinaryReader(webResponse.GetResponseStream())) {
            readResponseStream(reader);
        }
    }
  }
}