几天来，我一直在为这件事绞尽脑汁，我需要向社会提出这个问题.我用C#开发已经有一段时间了，但对实际使用异步非常陌生.我正在制作一个rest API客户端，并决定使用RestSharp.我希望使用Execute或ExecuteTaskAsync，但似乎自从我上次查看RestSharp以来，这两个方法已被弃用，因此看起来我需要使RestClient上的ExecuteAsync工作.

在过go 的几天里，我一直在搜索StackOverflow和其他参考文献，试图梳理这一点.大多数参考资料似乎都很陈旧，它们都提到了几年前的Execute或ExecuteTaskAsync，所以我从所有这些来源中拼凑了出来，并花费了大量时间进行测试和重写.

我能够让下面的实现针对真实的API工作(出于业务目的调整了一些变量)，但是类的实现工作得很好.它返回预期的RestResponse，我可以从中获取RestResponse.Content.

但是，当我try 为该方法设置单元测试时，在使用模拟版本的IRestClient时遇到了方法失败的问题.它一直说我有一个NullReferenceExcption，但不清楚问题的确切位置.对于这个样例，我使用的是.netFramework4.8和RestSharpv110.2.0.0.

作为异步的新手，我已经try 了各种不同的方法来配置模拟设置和返回，但我愿意判断和测试您可能对此有建议的任何其他配置.任何帮助我弄清楚我在哪里/为什么得到空引用的帮助都是非常感谢的.谢谢!

Class

using RestSharp;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace MyLib.Classes.Samples
{
    public interface IAuthSample
    {
        string GetResponse();
        Task<RestResponse> MakeAuthApiCallAsync();
    }

    public class AuthSample : IAuthSample
    {
        public string Url;
        public string Key;
        public string Secret;
        public IRestClient Client;

        public string GetResponse()
        {
            this.Url = "http://test.com";
            this.Key = "12345";
            this.Secret = "54321";

            var response = MakeAuthApiCallAsync().GetAwaiter().GetResult();
            return response.Content;
        }


        public virtual async Task<RestResponse> MakeAuthApiCallAsync()
        {
            var options = new RestClientOptions(this.Url)
            {
                MaxTimeout = -1,
            };

            // Set up api request
            var request = new RestRequest("oauth/token", Method.Post);
            request.AddHeader("Content-Type", "application/x-www-form-urlencoded");

            request.AddParameter("grant_type", "client_credentials");
            request.AddParameter("client_id", this.Key);
            request.AddParameter("client_secret", this.Secret);

            // Set up rest client if it doesn't exist
            IRestClient client = this.Client ?? new RestClient(options);

            // Contact api and get result
            var task = await client.ExecuteAsync<RestResponse>(request, CancellationToken.None);

            return task;
        }
    }
}

Unit Test

using MyLib.Classes;
using Moq;
using RestSharp;
using System.Net;
using MyLib.Classes.Samples;

namespace MyLib.Test.Classes.Samples
{
    [TestFixture()]
    public class AuthSampleTests
    {
        [Test()]
        public void GetResponseTest()
        {
            Assert.Fail();
        }

        [Test()]
        public void TestMakeAuthApiCall_SupplyParameters_MatchResponseResults()
        {

            // Arrange

            var url = "http://test.com";
            var key = "12345";
            var secret = "54321";
            var auth = new AuthSample()
            {
                Url = url,
                Key = key,
                Secret = secret
            };
            

            var response = new RestResponse()
            {
                Content = "blah",
                StatusCode = HttpStatusCode.OK
            };

            var restClient = new Mock<IRestClient>() { CallBase = true };

            restClient.Setup(x => x.ExecuteAsync(It.IsAny<RestRequest>(), It.IsAny<CancellationToken>()))
                .ReturnsAsync(response);

            auth.Client = restClient.Object;

            // Act

            var result = auth.MakeAuthApiCallAsync().GetAwaiter().GetResult();

            // Assert

            Assert.Fail();

        }
    }
}

Exception and Stack

System.NullReferenceException
  HResult=0x80004003
  Message=Object reference not set to an instance of an object.
  Source=RestSharp
  StackTrace:
   at RestSharp.RestClientExtensions.<ExecuteAsync>d__10`1.MoveNext()
   at MyLib.Classes.Samples.AuthSample.<MakeAuthApiCallAsync>d__5.MoveNext() in C:\Users\bb\Documents\My Samples\VS Samples\MyApi\MyLib\Classes\Samples\AuthSample.cs:line 54

  This exception was originally thrown at this call stack:
    MyLib.Classes.Samples.AuthSample.MakeAuthApiCallAsync() in AuthSample.cs