使用起订量嘲笑为一个单元测试的异步方法 [英] Using Moq to mock an asynchronous method for a unit test
问题描述
我测试了，让一个Web API 呼叫服务的方法。使用普通的的HttpClient 工作正常进行单元测试，如果我还运行Web服务（位于另一个项目中的溶液）本地。
I am testing a method for a service that makes a Web API call. Using a normal HttpClient works fine for unit tests if I also run the web service (located in another project in the solution) locally.
然而，当我在变化检查构建服务器将无法访问该Web服务，以便测试将失败。
However when I check in my changes the build server won't have access to the web service so the tests will fail.
我想出解决的办法通过创建一个 IHttpClient 接口和实施，我在我的应用程序中使用的版本我的单元测试。单元测试，我做一个嘲笑完整版用嘲笑的异步POST方法。这里就是我所遇到的问题。我想返回一个OK HttpStatusResult 为这个特殊的测试。对于另一个类似的测试，我将返回一个坏的结果。
I've devised a way around this for my unit tests by creating an IHttpClient interface and implementing a version that I use in my application. For unit tests, I make a mocked version complete with a mocked asynchronous post method. Here's where I have run into problems. I want to return an OK HttpStatusResult for this particular test. For another similar test I will be returning a bad result.
该测试将运行，但将永远不会完成。它挂在游览车。我是新来的异步编程，委托和起订量本身，我一直很搜索和谷歌一段时间学习新的东西，但我似乎仍不能让过去这个问题。
The test will run but will never complete. It hangs at the await. I am new to asynchronous programming, delegates, and Moq itself and I've been searching SO and google for a while learning new things but I still can't seem to get past this problem.
下面是方法，我想测试一下：
Here is the method I am trying to test:
public async Task<bool> QueueNotificationAsync(IHttpClient client, Email email)
{
// do stuff
try
{
// The test hangs here, never returning
HttpResponseMessage response = await client.PostAsync(uri, content);
// more logic here
}
// more stuff
}
下面是我的单元测试方法：
Here's my unit test method:
[TestMethod]
public async Task QueueNotificationAsync_Completes_With_ValidEmail()
{
Email email = new Email()
{
FromAddress = "bob@example.com",
ToAddress = "bill@example.com",
CCAddress = "brian@example.com",
BCCAddress = "ben@example.com",
Subject = "Hello",
Body = "Hello World."
};
var mockClient = new Mock<IHttpClient>();
mockClient.Setup(c => c.PostAsync(
It.IsAny<Uri>(),
It.IsAny<HttpContent>()
)).Returns(() => new Task<HttpResponseMessage>(() => new HttpResponseMessage(System.Net.HttpStatusCode.OK)));
bool result = await _notificationRequestService.QueueNotificationAsync(mockClient.Object, email);
Assert.IsTrue(result, "Queue failed.");
}
我在做什么错了？
What am I doing wrong?
感谢您的帮助。
推荐答案
您正在创建的任务，但从来没有启动它，所以它永远不会完成。但是，不要刚开始的任务 - 相反，改为使用<一个href=\"http://msdn.microsoft.com/en-us/library/hh194922%28v=vs.110%29.aspx\"><$c$c>Task.FromResult<TResult>这将给你它已经完成的任务：
You're creating a task but never starting it, so it's never completing. However, don't just start the task - instead, change to using Task.FromResult<TResult> which will give you a task which has already completed:
...
.Returns(Task.FromResult(new HttpResponseMessage(System.Net.HttpStatusCode.OK)));
请注意，你将不会被这种方式测试实际的异步 - 如果你想做到这一点，你需要做一些更多的工作，以创建一个任务＆LT; T＆GT; ，你可以在一个更精细的方式控制......但是这件事情的另一天。
Note that you won't be testing the actual asynchrony this way - if you want to do that, you need to do a bit more work to create a Task<T> that you can control in a more fine-grained manner... but that's something for another day.
您可能还需要考虑使用一个假的 IHttpClient ，而不是嘲讽一切 - 这真的取决于你需要多久它
You might also want to consider using a fake for IHttpClient rather than mocking everything - it really depends on how often you need it.
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