如何在.NET测试中传入一个模拟的HttpClient？

Question

我有一个Microsoft.Net.Http用于检索一些Json数据的服务.大!

当然,我不希望我的单元测试击中实际的服务器(否则,这是一个集成测试).

这是我的服务ctor(使用依赖注入......)

public Foo(string name, HttpClient httpClient = null)
{
...
}

我不知道我怎么可以......比如嘲笑这个.. Moq或FakeItEasy.

我想确保当我的服务电话GetAsync或PostAsync..然后我可以伪造这些电话.

有什么建议我怎么做？

我希望 - 我不需要制作我自己的Wrapper ..因为这是废话:(微软不能对此进行疏忽,对吧？

(是的,它很容易制作包装..我之前已经完成了它们......但这是重点!)

Answer 1

您可以用假的核心HttpMessageHandler替换它.看起来像这样......

public class FakeResponseHandler : DelegatingHandler
    {
        private readonly Dictionary<Uri, HttpResponseMessage> _FakeResponses = new Dictionary<Uri, HttpResponseMessage>(); 

        public void AddFakeResponse(Uri uri, HttpResponseMessage responseMessage)
        {
                _FakeResponses.Add(uri,responseMessage);
        }

        protected async override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, System.Threading.CancellationToken cancellationToken)
        {
            if (_FakeResponses.ContainsKey(request.RequestUri))
            {
                return _FakeResponses[request.RequestUri];
            }
            else
            {
                return new HttpResponseMessage(HttpStatusCode.NotFound) { RequestMessage = request};
            }

        }
    }

然后你可以创建一个使用假处理程序的客户端.

var fakeResponseHandler = new FakeResponseHandler();
fakeResponseHandler.AddFakeResponse(new Uri("http://example.org/test"), new HttpResponseMessage(HttpStatusCode.OK));

var httpClient = new HttpClient(fakeResponseHandler);

var response1 = await httpClient.GetAsync("http://example.org/notthere");
var response2 = await httpClient.GetAsync("http://example.org/test");

Assert.Equal(response1.StatusCode,HttpStatusCode.NotFound);
Assert.Equal(response2.StatusCode, HttpStatusCode.OK);

Answer 2

我知道这是一个老问题,但我在搜索这个主题时偶然发现了它,并找到了一个非常好的解决方案,使测试HttpClient更容易.

它可以通过nuget获得:

https://github.com/richardszalay/mockhttp

PM> Install-Package RichardSzalay.MockHttp

以下是对使用情况的快速了解:

var mockHttp = new MockHttpMessageHandler();

// Setup a respond for the user api (including a wildcard in the URL)
mockHttp.When("http://localost/api/user/*")
        .Respond("application/json", "{'name' : 'Test McGee'}"); // Respond with JSON

// Inject the handler or client into your application code
var client = new HttpClient(mockHttp);

var response = await client.GetAsync("http://localost/api/user/1234");
// or without await: var response = client.GetAsync("http://localost/api/user/1234").Result;

var json = await response.Content.ReadAsStringAsync();

// No network connection required
Console.Write(json); // {'name' : 'Test McGee'}

有关github项目页面的更多信息.希望这可能有用.