c# - 无法在单元测试中模拟 HttpClient PostAsync()

Question

我正在使用 xUnit 和 Moq 编写测试用例。

我正在尝试模拟 HttpClient 的 PostAsync()，但出现错误。

下面是用于模拟的代码:

   public TestADLS_Operations()
    {
        var mockClient = new Mock<HttpClient>();
        mockClient.Setup(repo => repo.PostAsync(It.IsAny<string>(), It.IsAny<HttpContent>())).Returns(() => Task.FromResult(new HttpResponseMessage(HttpStatusCode.OK)));

        this._iADLS_Operations = new ADLS_Operations(mockClient.Object);
    }

错误:

Unsupported expression: repo => repo.PostAsync(It.IsAny(), It.IsAny()) Non-overridable members (here: HttpClient.PostAsync) may not be used in setup / verification expressions.

截图:

Answer 1

Non-overridable members (here: HttpClient.PostAsync) may not be used in setup / verification expressions.

我也试图 mock HttpClient和你一样，我得到了同样的错误信息。

解决方法:
而不是 mock HttpClient , mock HttpMessageHandler .
然后给mockHttpMessageHandler.Object给您的 HttpClient ，然后您将其传递给您的产品代码类。这是有效的，因为 HttpClient用途 HttpMessageHandler引擎盖下:

// Arrange
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);
this._iADLS_Operations = new ADLS_Operations(client);

注意:您还需要一个

using Moq.Protected;

在测试文件的顶部。
然后您可以调用使用 PostAsync 的方法来自您的测试，以及 PostAsync将返回 HTTP 状态 OK 响应:

// Act
var returnedItem = this._iADLS_Operations.MethodThatUsesPostAsync(/*parameter(s) here*/);

优势:
mock HttpMessageHandler意味着您的产品代码或测试代码中不需要额外的类。

有用的资源:

Unit Testing with the HttpClient

How to mock HttpClient in your .NET / C# unit tests