单元测试 DelegatingHandler

Question

如何对自定义 DelegatingHandler 进行单元测试？我有以下内容，但它抱怨未设置 innerHandler。

var httpRequestMessage = new HttpRequestMessage(HttpMethod.Get, "http://foo.com");
var handler = new FooHandler()
{
    InnerHandler = new FooHandler() 
};

var invoker = new HttpMessageInvoker(handler);
var result = await invoker.SendAsync(httpRequestMessage, new CancellationToken());

Assert.That(result.Headers.GetValues("some-header").First(), Is.Not.Empty, "");

Answer 1

您可以使用 dummy/fake 处理程序 (TestHandler) 设置您正在测试的 DelegatingHandler (FooHandler) 的 InnerHandler 属性，如图所示在您的评论中 that linked post。

public class TestHandler : DelegatingHandler
{
    protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        return Task.Factory.StartNew(() => new HttpResponseMessage(HttpStatusCode.OK), cancellationToken);
    }
}

 // in your test class method
    var httpRequestMessage = new HttpRequestMessage(HttpMethod.Get, "https://example.com/");
    var handler = new FooHandler()
    {
        InnerHandler = new TestHandler()  // <-- change to use this

    };

    var invoker = new HttpMessageInvoker(handler);
    var result = await invoker.SendAsync(httpRequestMessage, new CancellationToken());

    Assert.That(result.Headers.GetValues("some-header").First(), Is.Not.Empty, "");

与 post 不同，这应该是使测试达到运行所需的最低设置。

Answer 2

使用例如System.Net.Http.HttpClientHandler or System.Web.Http.HttpServer 作为 InnerHandler:

var handler = new FooHandler()
{
    InnerHandler = new System.Net.Http.HttpClientHandler()
};

或

var handler = new FooHandler()
{
    InnerHandler = new System.Web.Http.HttpServer() 
};

Answer 3

使用 using Moq.Protected;，您可以更好地控制响应结果。

var request = new HttpRequestMessage();

var innerHandlerMock = new Mock<DelegatingHandler>(MockBehavior.Strict);
innerHandlerMock
  .Protected()
  .Setup<Task<HttpResponseMessage>>("SendAsync", request, ItExpr.IsAny<CancellationToken>())
  .ReturnsAsync(new HttpResponseMessage(HttpStatusCode.OK));

var handler = new FooHandler()
{
  InnerHandler = innerHandlerMock.Object
};
var invoker = new HttpMessageInvoker(handler);

// act
await invoker.SendAsync(request, default);

单元测试 DelegatingHandler

Unit testing DelegatingHandler

c#

unit-testing

asp.net-web-api

delegatinghandler