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c# - XUnit 模拟方法但不返回预期结果

问题描述

我在 XUnit 测试中使用 moq，但由于某种原因，模拟无法正常工作。这是我的单元测试：

 [Fact]
        public async Task SampleUnitTest()
        {
            //Arrange
            var httpClient = new HttpClient(new FakeHttpMessageHandler());
            _mockConstructRequest.Setup(x => x.ConstructRequestString(searchRequestModel))
                                 .Returns("a sample string");
            var service = new LibraryService(_mockConstructRequest.Object);

            //Act
            var response = service.GetResponse(new Request(), httpClient);

            //Assert
            response.Should().BeNull();

        }

         private class FakeHttpMessageHandler : HttpMessageHandler
        {
            public Func<HttpRequestMessage, CancellationToken, HttpResponseMessage> HttpRequestHandler { get; set; } =
            (r, c) =>
                new HttpResponseMessage
                {
                    ReasonPhrase = r.RequestUri.AbsoluteUri,
                    StatusCode = HttpStatusCode.OK
                };


            protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
            {
                return Task.FromResult(HttpRequestHandler(request, cancellationToken));
            }
        }

这是实际的代码，我正在尝试测试GetResponse方法。

  public class LibraryService : ILibraryService
 {
    private IConfiguration _configuration;
    private IRequestConstructor _requestContructor;
    public LibraryService (IRequestConstructor requestConstructor)
    {
        _requestConstructor = requestConstructor;
    }

    public async Task<Response> GetResponse(Request request, HttpClient client)
        {

            //construct request
            string requestString = _constructRequestString.ConstructRequestString(request, client);

            return null;
        }
 }

 public class RequestContructor : IRequestContructor
 {
  public string ConstructRequestString(Request request)
        {
            return "a request string";
        }
 }

我试图从我的单元测试中单步执行代码，但是当断点位于这一行时，requestString变量为空，而它应该返回“示例字符串”。有谁知道为什么？

string requestString = _constructRequestString.ConstructRequestString(request, client);

标签： c#moqxunit

解决方案

据我所见，您的模拟不正确：您的模拟：

_mockConstructRequest.Setup(x => x.ConstructRequestString(searchRequestModel))
                                 .Returns("a sample string");

您正在调用的方法：

_constructRequestString.ConstructRequestString(request, client);

不应该是这样的：

_mockConstructRequest.Setup(x => x.ConstructRequestString(It.IsAny<Request>(),It.IsAny<HttpClient>()))
                                 .Returns("a sample string");

最重要的是：

尝试在构造函数中而不是在每个测试中初始化你的模拟和你的“classUnderTest”，它会在每次测试前运行并为你做所有事情。例如：

public class UnitTestClass{

private readonly ClassUnderTest _classUnderTest;
private readonly Mock<ClassUnderTestDependecy> mockedInstance;

public UnitTestClass {
mockedInstance= new Mock<ClassUnderTestDependecy>();
_classUnderTest= new ClassUnderTest (ClassUnderTestDependecy.Object);
}

}

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