遇到无法在进行集成测试时加载一个或多个请求的类型

Question

我正在使用Target Famrwework 4.6对asp.net核心API进行集成测试，因为该项目需要我的一些旧的4.6 dll。我收到以下错误。

消息：System.Reflection.ReflectionTypeLoadException：无法加载一个或多个请求的类型。检索LoaderExceptions属性以获取更多信息。

当我调用await _client.GetAsync 时出现错误

我附上了StackTace图片。

我的测试项目是一个类库框架4.6。

TestFixture.cs

 public class TestFixture :IDisposable
    {
        private const string SolutionName = "Project.API.sln";
        private readonly TestServer _server;

        public HttpClient Client { get; }

        public TestFixture()
        {
            Assembly startAssembly = typeof(Startup).GetTypeInfo().Assembly;
            var contentRoot = GetProjectPath(startAssembly);
            var builder = new WebHostBuilder()
                .UseContentRoot(contentRoot)
                .UseEnvironment("Development")
                .UseStartup<Startup>();

            _server = new TestServer(builder);
            Client = _server.CreateClient();
            Client.BaseAddress = new Uri("http://localhost:62455");
        }

        public string GetProjectPath(Assembly startupAssembly)
        {
            var projectName = startupAssembly.GetName().Name;
            var applicationBasePath = PlatformServices.Default.Application.ApplicationBasePath;
            DirectoryInfo directoryInfo = new DirectoryInfo(applicationBasePath);
            do
            {
                var solutionFileInfo = new FileInfo(Path.Combine(directoryInfo.FullName, SolutionName));
                if (solutionFileInfo.Exists)
                {
                    return Path.GetFullPath(Path.Combine(directoryInfo.FullName, projectName));
                }
                directoryInfo = directoryInfo.Parent;
            }
            while (directoryInfo.Parent != null);
            throw new Exception($"Solution root could be located using application root {applicationBasePath}");
        }

        public void Dispose()
        {
            Client.Dispose();
            _server.Dispose();
        }
    }

test.cs中

 public class TransactionControllerTest :IClassFixture<TestFixture>
    {
        private string businessID = "1206";
        private readonly HttpClient _client;
        public TransactionControllerTest(TestFixture fixture)
        {
            _client = fixture.Client;
        }
        [Fact]
        public async void ProcessFinalTransactionProcess()
        {
            var response = await _client.GetAsync($"/v1/businesses/{businessID}/transactions/TestMe");
            Assert.NotNull(response);
        }
    }