使用Moq将参数修改为虚拟无效方法

Question

我有一点完美的风暴阻止了我测试课程。该课程是RestClient，它包装了内部的HttpClient（我不能修改）。 HttpClient上的ExecuteMethod方法无效。它接受IHttpMethod，并根据来自服务器的响应修改此对象。我想嘲笑ExecuteMethod，以便它为我修改IHttpMethod。我正在尝试使用Callback来实现此目的，但它不起作用。

这里的发送请求的代码：

var httpClient = this.httpClientFactory.CreateHttpClient(); 
httpClient.ExecuteMethod(method); 

var response = this.GetResourceResponse<T>(method.ResponseBodyAsStream.AsString()); 
response.ResponseHeaders = method.ResponseHeaders; 
response.Status = method.StatusCode.ToString(); 
response.StatusCode = (int)method.StatusCode; 

return response; 

这是我的企图在嘲讽：

var mockHttpMethod = new Mock<IHttpMethod>(); 
mockHttpMethod.Setup(m => m.ResponseBodyAsStream).Returns(new MemoryStream(Encoding.UTF8.GetBytes("foo"))); 

var modifyHttpMethod = new Action<IHttpMethod>(m => 
{ 
    m = mockHttpMethod.Object; 
}); 

var mockHttpClient = new Mock<IHttpClient>(); 
mockHttpClient.Setup(c => c.ExecuteMethod(It.IsAny<IHttpMethod>())) 
    .Callback<IHttpMethod>(modifyHttpMethod); 

var mockHttpClientFactory = new Mock<ILegalHoldHttpClientFactory>(); 
mockHttpClientFactory.Setup(f => f.CreateHttpClient()).Returns(mockHttpClient.Object); 

var restClient = new RestClient(mockHttpClientFactory.Object); 

当执行modifyHttpMethod行动，我看到两件事情，这两者我期待：

1. 传入IHttpMethod（m）有p我期望它具有的性能。
2. 将模拟对象分配给m后，它包含我在测试中设置的残段值。

然而，在执行后回调，并控制返回到我的应用程序的代码，我method变量仍然有我在上面的步骤1，尝试读取method.ResponseBodyAsStream时导致空引用异常看到了它的旧值。

我试图做什么甚至可以实现？如果是这样，怎么样？谢谢！

Answer 1

我复制你的设置相一相嘲讽，并不能找到它的任何问题：

public interface IHttpMethod 
{ 
    MemoryStream ResponseBodyAsStream { get; set; } 
} 

public interface IHttpClient 
{ 
    void ExecuteMethod(IHttpMethod method); 
} 

public class HttpClient : IHttpClient 
{ 

    #region IHttpClient Members 

    public void ExecuteMethod(IHttpMethod method) 
    { 

    } 

    #endregion 
} 

public class Factory 
{ 
    public virtual IHttpClient CreateHttpClient() 
    { 
     return new HttpClient(); 
    } 
} 

public class ClassUnderTest 
{ 
    private readonly Factory _factory; 

    public ClassUnderTest(Factory factory) 
    { 
     _factory = factory; 
    } 

    public string GetResponseAsString(IHttpMethod method) 
    { 
     var myClient = _factory.CreateHttpClient(); 
     myClient.ExecuteMethod(method); 

     return method.ResponseBodyAsStream.ToString(); 
    } 
} 

[TestClass] 
public class ScratchPadTest 
{ 
    [TestMethod] 
    public void SampleTest() 
    { 
     var mockHttpMethod = new Mock<IHttpMethod>(); 
     mockHttpMethod.Setup(x => x.ResponseBodyAsStream).Returns(new MemoryStream(Encoding.UTF8.GetBytes("foo"))); 

     var modifyHttpMethod = new Action<IHttpMethod>(m => 
     { 
      m = mockHttpMethod.Object; 
     }); 

     var mockHttpClient = new Mock<IHttpClient>(); 
     mockHttpClient.Setup(c => c.ExecuteMethod(It.IsAny<IHttpMethod>())).Callback<IHttpMethod>(modifyHttpMethod); 

     var myFactoryStub = new Mock<Factory>(); 
     myFactoryStub.Setup(f => f.CreateHttpClient()).Returns(mockHttpClient.Object); 

     var myCut = new ClassUnderTest(myFactoryStub.Object); 

     Assert.IsNotNull(myCut.GetResponseAsString(mockHttpMethod.Object)); 
    } 

} 

该测试通过，这意味着内存流不为空（否则一个例外是生成）。我可以看到的唯一X因素是你的AsString（）扩展方法（我假设这是一个扩展方法，因为intellisense并没有在MemoryStream中显示给我）。你的问题能在那里吗？

而且，顺便说一句，你试图做的事情几乎可以肯定是用Moq实现的。