public class CookieStartup
{
    public override void Configuration
    {
        app.UseCookieAuthentication(options)
    }
}

[SetUp]
public void SetUp()
{
    _mockAuthListManager = new Mock<IAuthenticationListManager>();

    ApplicationUrl = ApplicationFactory.Create<CookieStartup>();
    Client = new HttpClient(HttpClientHandler)
    {
        BaseAddress = new Uri(ApplicationUrl),
    };
}

[Test]
public void RequestWithCookie_Succeeds()
{
    FetchCookie();

    var response = Client.GetAsync(ApplicationUrl).Result;

    response.EnsureSuccessStatusCode();
}

internal string Create<T>()
{
    string thisUrl = "http://localhost:" + FreeTCPPort();
    _app = WebApp.Start<T>(thisUrl);

    return thisUrl;
}