[英]How can I test a custom DelegatingHandler in the ASP.NET MVC 4 Web API?
我在幾個地方看到過這個問題,但沒有看到任何好的答案。 由於我不得不自己做幾次,我想我會發布我的解決方案。 如果你有更好的,請留言。
注意這是使用 ASP.NET MVC 4 Beta 2 版本的 Web API - 未來版本可能會改變!
更新:這仍然適用於 ASP.NET MVC 4 RC
在這種方法中,我創建了一個 TestHandler 並將其設置為InnerHandler
處理程序的InnerHandler
屬性。
然后可以將被測處理程序傳遞給HttpClient
- 如果您正在編寫服務器端處理程序,這可能看起來不直觀,但這實際上是測試處理程序的一種很好的輕量級方法 - 它將以與它相同的方式調用將在服務器中。
默認情況下,TestHandler 只會返回一個 HTTP 200,但它的構造函數接受一個函數,您可以使用它對從被測處理程序傳入的請求消息進行斷言。 最后,您可以對來自客戶端的 SendAsync 調用的結果進行斷言。
設置完所有內容后,在客戶端實例上調用SendAsync
以調用您的處理程序。 請求將被傳遞到您的處理程序中,它會將其傳遞給 TestHandler(假設它傳遞了調用),然后它將響應返回給您的處理程序。
測試處理程序如下所示:
public class TestHandler : DelegatingHandler
{
private readonly Func<HttpRequestMessage,
CancellationToken, Task<HttpResponseMessage>> _handlerFunc;
public TestHandler()
{
_handlerFunc = (r, c) => Return200();
}
public TestHandler(Func<HttpRequestMessage,
CancellationToken, Task<HttpResponseMessage>> handlerFunc)
{
_handlerFunc = handlerFunc;
}
protected override Task<HttpResponseMessage> SendAsync(
HttpRequestMessage request, CancellationToken cancellationToken)
{
return _handlerFunc(request, cancellationToken);
}
public static Task<HttpResponseMessage> Return200()
{
return Task.Factory.StartNew(
() => new HttpResponseMessage(HttpStatusCode.OK));
}
}
測試中想象的MyHandler
示例用法。 使用 NUnit 進行斷言。:
var httpRequestMessage = new HttpRequestMessage(HttpMethod.Get, "http://test.com");
httpRequestMessage.Headers.Add("username", "test");
var handler = new MyHandler()
{
InnerHandler = new TestHandler((r,c) =>
{
Assert.That(r.Headers.Contains("username"));
return TestHandler.Return200();
})
};
var client = new HttpClient(handler);
var result = client.SendAsync(httpRequestMessage).Result;
Assert.That(result.StatusCode, Is.EqualTo(HttpStatusCode.OK));
TestHandler 的默認行為可能適用於許多測試,並使代碼更簡單。 被測處理程序的設置如下所示:
var handler = new MyHandler();
handler.InnerHandler = new TestHandler();
我喜歡這種方法,因為它保留了測試方法中的所有斷言,並且TestHandler
非常可重用。
我只是在尋找同樣的東西,但想出了一種更簡潔的方法,不使用 http 客戶端。 我想要一個測試來斷言消息處理程序消耗了一個模擬的日志組件。 我真的不需要內部處理程序來運行,只是為了滿足單元測試而“存根”它。 為我的目的工作:)
//ARRANGE
var logger = new Mock<ILogger>();
var handler= new ServiceLoggingHandler(logger.Object);
var request = ControllerContext.CreateHttpRequest(Guid.NewGuid(), "http://test",HttpMethod.Get);
handler.InnerHandler = new Mock<HttpMessageHandler>(MockBehavior.Loose).Object;
request.Content = new ObjectContent<CompanyRequest>(Company.CreateCompanyDTO(), new JsonMediaTypeFormatter());
var invoker = new HttpMessageInvoker(handler);
//ACT
var result = invoker.SendAsync(request, new System.Threading.CancellationToken()).Result;
//ASSERT
<Your assertion>
我創建了以下用於測試 DelegatingHandlers 的內容。 對於使用 HttpRequestMessage.DependencyScope 使用您最喜歡的 IoC 框架(例如,帶有 WindsorContainer 的 WindsorDependencyResolver 來解析依賴項的處理程序)非常有用:
public class UnitTestHttpMessageInvoker : HttpMessageInvoker
{
private readonly HttpConfiguration configuration;
public UnitTestHttpMessageInvoker(HttpMessageHandler handler, IDependencyResolver resolver)
: base(handler, true)
{
this.configuration = new HttpConfiguration();
configuration.DependencyResolver = resolver;
}
[DebuggerNonUserCode]
public override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
if (request == null)
{
throw new ArgumentNullException("request");
}
request.Properties["MS_HttpConfiguration"] = this.configuration;
return base.SendAsync(request, cancellationToken);
}
}
我也找到了這個答案,因為我有我的自定義處理程序,我想測試它我們正在使用 NUnit 和 Moq,所以我認為我的解決方案可能對某人有所幫助
using Moq;
using Moq.Protected;
using NUnit.Framework;
namespace Unit.Tests
{
[TestFixture]
public sealed class Tests1
{
private HttpClient _client;
private HttpRequestMessage _httpRequest;
private Mock<DelegatingHandler> _testHandler;
private MyCustomHandler _subject;//MyCustomHandler inherits DelegatingHandler
[SetUp]
public void Setup()
{
_httpRequest = new HttpRequestMessage(HttpMethod.Get, "/someurl");
_testHandler = new Mock<DelegatingHandler>();
_subject = new MyCustomHandler // create subject
{
InnerHandler = _testHandler.Object //initialize InnerHandler with our mock
};
_client = new HttpClient(_subject)
{
BaseAddress = new Uri("http://localhost")
};
}
[Test]
public async Task Given_1()
{
var mockedResult = new HttpResponseMessage(HttpStatusCode.Accepted);
void AssertThatRequestCorrect(HttpRequestMessage request, CancellationToken token)
{
Assert.That(request, Is.SameAs(_httpRequest));
//... Other asserts
}
// setup protected SendAsync
// our MyCustomHandler will call SendAsync internally, and we want to check this call
_testHandler
.Protected()
.Setup<Task<HttpResponseMessage>>("SendAsync", _httpRequest, ItExpr.IsAny<CancellationToken>())
.Callback(
(Action<HttpRequestMessage, CancellationToken>)AssertThatRequestCorrect)
.ReturnsAsync(mockedResult);
//Act
var actualResponse = await _client.SendAsync(_httpRequest);
//check that internal call to SendAsync was only Once and with proper request object
_testHandler
.Protected()
.Verify("SendAsync", Times.Once(), _httpRequest, ItExpr.IsAny<CancellationToken>());
// if our custom handler modifies somehow our response we can check it here
Assert.That(actualResponse.IsSuccessStatusCode, Is.True);
Assert.That(actualResponse, Is.EqualTo(mockedResult));
//...Other asserts
}
}
}
另一種選擇可能是存根
public class TestingHandlerStub : DelegatingHandler
{
private readonly Func<HttpRequestMessage, CancellationToken, Task<HttpResponseMessage>> _handlerFunc;
public TestingHandlerStub(Func<HttpRequestMessage, CancellationToken, Task<HttpResponseMessage>> handlerFunc)
{
_handlerFunc = handlerFunc;
}
protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
return _handlerFunc(request, cancellationToken);
}
}
這是如何結合:
var handler = new YourCustomHandler()
{
InnerHandler = new TestingHandlerStub((r, c) =>
{
return Task.FromResult(httpResponseMessage);
})
};
var client = new HttpClient(handler);
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