Flurl＆HttpTest：单元测试在全部运行时失败，但在单独运行时通过

Question

Update: HttpTest is not thread-safe, as per the project's GitHub issue . Until the issue is resolved, tests using HttpTest cannot be run in parallel.

I have a really weird pair of test utilizing Flurl and xUnit that, when Run All in VS Test Explorer, will fail, but if run individually, will pass. I cannot for the life of me see anywhere where the 2 are even related to each other, but they do.

I have extracted them out of my project into a new project and the problem persists. I bundled them into a 7z for anyone interested in loading it to VS, but the full code follows.

Project.Commons

GetApi1:

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Flurl;
using Flurl.Http;

namespace Project.Commons
{
    public class GetApi1
    {

        public async Task<string> ExecuteAsync(string token)
        {
            string apikeyKeyname = "token";

            dynamic response = await "http://www.api.com"
                .SetQueryParams(new { token = token })
                .GetJsonAsync();

            string receivedApiKey = ((IDictionary<string, object>)response)[apikeyKeyname].ToString();

            return receivedApiKey;
        }
    }
}

GetApi2:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Flurl;
using Flurl.Http;

namespace Project.Commons
{
    public class GetApi2
    {
        public async Task<IList<string>> ExecuteAsync()
        {
            var responses = await "http://www.api.com"
                .GetJsonAsync<List<string>>();

            var result = new List<string>();

            foreach (var response in responses)
            {
                result.Add("refined stuff");
            }

            return result;
        }
    }
}

Project.Tests

UnitTest1:

using Project.Commons;

namespace Project.Tests
{
    public class UnitTest1
    {
        private ITestOutputHelper output;
        public UnitTest1(ITestOutputHelper output)
        {
            this.output = output;
        }

        [Fact]
        public async Task ShouldBeAbleToGetApiKeyFromToken()
        {
            // Arrange
            using (var httpTest = new HttpTest())
            {
                var jsonResponse = new { token = "abcdef" };
                string expectedApiKey = "abcdef";
                httpTest.RespondWithJson(jsonResponse);
                var api = new GetApi1();

                // Act
                var receivedApiKey = await api.ExecuteAsync("mockToken");
                output.WriteLine("Received apikey = " + receivedApiKey);

                // Assert
                Assert.Equal(expectedApiKey, receivedApiKey);
            }
        }
    }
}

UnitTest2

using Flurl.Http.Testing;
using Project.Commons;
using Xunit;
using Xunit.Abstractions;

namespace Project.Tests
{
    public class UnitTest2
    {


        #region Mock API JSON Response
        private IList<string> mockResponse = new List<string>()
        {
            "raw stuff", "raw stuff", "raw stuff"
        };
        #endregion

        #region Expected Result
        private IList<string> expectedResult = new List<string>()
        {
            "refined stuff", "refined stuff", "refined stuff"
        };
        #endregion

        [Fact]
        public async Task CanGetProjectsByWeek()
        {
            // Arrange
            using (var httpTest = new HttpTest())
            {
                httpTest.RespondWithJson(mockResponse);

                // Act
                var api = new GetApi2();
                var actualResult = await api.ExecuteAsync();

                // Assert
                Assert.Equal(expectedResult,actualResult);
            }
        }
    }
}

Answer 1

The comments are correct - lack of thread safety is a known limitation of HttpTest. It is logged and under investigation. Parallel testing is much more prevalent today than just a couple years ago when this was created, so while a fix is not trivial, we are treating it with high priority.