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innerHandler没有设置。

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

您可以使用虚拟/假处理程序( InnerHandler )设置要测试的DelegatingHandler (FooHandler)的FooHandler属性，如注释中的联系员额所示。

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

 // 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, "");

不像那篇文章，这应该是您需要设置的最低限度，以使您的测试运行。

Answer 2

使用using Moq.Protected;，您可以获得对响应结果的更多控制。

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);

Answer 3

例如使用System.Net.Http.HttpClientHandler或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() 
};