c# - 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，但它提示未设置 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

您可以使用虚拟/假处理程序 (TestHandler) 将您正在测试的 DelegatingHandler (FooHandler) 的 InnerHandler 属性设置为显示在 that linked post在您的评论中。

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, "");

与那篇文章不同，这应该是运行测试所需的最低设置。