.NET Core xUnit test for testing the middleware using TestHost package

DummyCookieMiddlewareTests.cs

using System;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Xunit;

namespace FirstWebApp.Tests
{
    public class DummyCookieMiddlewareTests
    {
        [Fact]
        public async Task GivenWebApp_WhenFirstRequestIsSentToWebApp_ThenDummyCookieIsAddedToResponse()
        {
            // Arrange
            var memoryStream = new MemoryStream();
            var testServer = await Setup.InitTestServer();

            // Act
            var resultContext = await testServer.SendAsync(context => {
                context.Response.Body = memoryStream;
                context.Request.Path = "/";            
            });
            
            // Assert 1: if the next delegate was invoked
            memoryStream.Position = 0;
            string responseBody = new StreamReader(memoryStream).ReadToEnd();
            Assert.Equal(Setup.ExpectedOutput, responseBody);

            // Assert 2: if the cookie is added to the response
            var setCookieHeaders = resultContext.Response.GetTypedHeaders().SetCookie;
            var cookie = setCookieHeaders?.FirstOrDefault(x => x.Name == "DummyCookie");
            Assert.True(Guid.TryParse(cookie.Value, out Guid result));
        }
    }
}