Question

我喜欢对使用<%= f.fields_for :questions do |builder| %>的类进行单元测试。我们在类构造函数中注入了_question_fields.html.erb对象。

HttpClient

现在我们想对HttpClient方法进行单元测试。我们使用public class ClassA : IClassA { private readonly HttpClient _httpClient; public ClassA(HttpClient httpClient) { _httpClient = httpClient; } public async Task<HttpResponseMessage> SendRequest(SomeObject someObject) { //Do some stuff var request = new HttpRequestMessage(HttpMethod.Post, "http://some-domain.in"); //Build the request var response = await _httpClient.SendAsync(request); return response; } }进行单元测试框架，使用ClassA.SendRequest进行模拟。

当我们尝试模仿Ms Test时，它会抛出Moq。

HttpClient

我们如何解决这个问题？

Answer 1

特定的重载方法不是虚拟的，因此无法被Moq覆盖。

public Task<HttpResponseMessage> SendAsync(HttpRequestMessage request);

这就是它抛出NotSupportedException

的原因

您正在寻找的虚拟方法是此方法

public virtual Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken);

然而，模拟HttpClient并不像内部消息处理程序那样简单。

我建议使用具有自定义消息处理程序存根的具体客户端，以便在伪造请求时提供更大的灵活性。

以下是委托处理程序存根的示例。

public class DelegatingHandlerStub : DelegatingHandler {
    private readonly Func<HttpRequestMessage, CancellationToken, Task<HttpResponseMessage>> _handlerFunc;
    public DelegatingHandlerStub() {
        _handlerFunc = (request, cancellationToken) => Task.FromResult(request.CreateResponse(HttpStatusCode.OK));
    }

    public DelegatingHandlerStub(Func<HttpRequestMessage, CancellationToken, Task<HttpResponseMessage>> handlerFunc) {
        _handlerFunc = handlerFunc;
    }

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

注意默认构造函数基本上是在做你之前尝试模拟的东西。它还允许使用委托代理的更多自定义方案。

使用存根，测试可以重构为类似

public async Task _SendRequestAsync_Test() {
    //Arrange           
    var handlerStub = new DelegatingHandlerStub();
    var client = new HttpClient(handlerStub);
    var sut = new ClassA(client);
    var obj = new SomeObject() {
        //Populate
    };

    //Act
    var response = await sut.SendRequest(obj);

    //Assert
    Assert.IsNotNull(response);
    Assert.IsTrue(response.IsSuccessStatusCode);
}

Answer 2

使用HttpClient进行模拟是很难的，因为它是在大多数人在dotnet中进行单元测试之前编写的。有时我会设置一个存根HTTP服务器，它根据与请求URL匹配的模式返回预设响应，这意味着您测试真实的HTTP请求而不是模拟，而是测试本地主机服务器。使用WireMock.net使这非常简单并且运行速度足以满足我的大部分单元测试需求。

因此，代替http://some-domain.in在某个端口上使用localhost服务器设置，然后：

var server = FluentMockServer.Start(/*server and port can be setup here*/);
server.Given(
      Request.Create()
      .WithPath("/").UsingPost()
   )
   .RespondWith(
       Response.Create()
       .WithStatusCode(200)
       .WithHeader("Content-Type", "application/json")
       .WithBody("{'attr':'value'}")
   );

您可以找到更多详情和guidance on using wiremock in tests here.

Answer 3

Moq可以模拟出受保护的方法，例如HttpMessageHandler上的SendAsync，您可以在其构造函数中提供给HttpClient。

var mockHttpMessageHandler = new Mock<HttpMessageHandler>();
mockHttpMessageHandler.Protected()
    .Setup<Task<HttpResponseMessage>>("SendAsync", ItExpr.IsAny<HttpRequestMessage>(), ItExpr.IsAny<CancellationToken>())
    .ReturnsAsync(new HttpResponseMessage
    {
        StatusCode = HttpStatusCode.OK
     });

var client = new HttpClient(mockHttpMessageHandler.Object);

从https://thecodebuzz.com/unit-test-mock-httpclientfactory-moq-net-core/复制

Answer 4

我最近不得不模拟 HttpClient，我使用了 Moq.Contrib.HttpClient。这是我需要的，而且使用起来很简单，所以我想我会把它扔在那里。

以下是一般用法的示例：

// All requests made with HttpClient go through its handler's SendAsync() which we mock
var handler = new Mock<HttpMessageHandler>();
var client = handler.CreateClient();

// A simple example that returns 404 for any request
handler.SetupAnyRequest()
    .ReturnsResponse(HttpStatusCode.NotFound);

// Match GET requests to an endpoint that returns json (defaults to 200 OK)
handler.SetupRequest(HttpMethod.Get, "https://example.com/api/stuff")
    .ReturnsResponse(JsonConvert.SerializeObject(model), "application/json");

// Setting additional headers on the response using the optional configure action
handler.SetupRequest("https://example.com/api/stuff")
    .ReturnsResponse(bytes, configure: response =>
    {
        response.Content.Headers.LastModified = new DateTime(2018, 3, 9);
    })
    .Verifiable(); // Naturally we can use Moq methods as well

// Verify methods are provided matching the setup helpers
handler.VerifyAnyRequest(Times.Exactly(3));

有关详细信息，请查看作者的博文 here。

使用Moq模拟HttpClient

4 个答案: