我终于开始讨论创建一些与RESTful Web界面一起使用的应用程序了,但是,我担心每次点击F5进行一系列测试时我都在锤击他们的服务器。
基本上,我需要获得一系列Web响应,以便我可以测试我正确解析变化的响应,而不是每次都打到他们的服务器,我想我可以这样做一次,保存XML然后在本地工作。
但是,我不知道如何“模拟”WebResponse,因为(AFAIK)它们只能通过 WebRequest.GetResponse
进行实例化。你们怎么去嘲笑这种事情?你呢?我真的不喜欢我正在锤击他们的服务器的事实:我不想更改代码太多,但我希望有一种优雅的方式来做这件事。
Will的回答是我所需要的一记耳光,我知道我错过了一个基本点!
一旦我敲了代码,我就会粘贴一些样本。
答案 0 :(得分:59)
我在寻找完全相同的事情时发现了这个问题。无法在任何地方找到答案,但经过一番挖掘后发现.Net Framework已经内置了对此的支持。
您可以使用WebRequest.RegisterPrefix
注册工厂对象,WebRequest.Create
在使用该前缀(或网址)时会调用该工厂对象。工厂对象必须实现IWebRequestCreate
,其中只有一个方法Create
,返回WebRequest
。在这里,您可以返回模拟WebRequest
。
我已经提供了一些示例代码 http://blog.salamandersoft.co.uk/index.php/2009/10/how-to-mock-httpwebrequest-when-unit-testing/
答案 1 :(得分:14)
这是一个不需要模拟的解决方案。您实现了WebRequest
的所有三个组成部分:IWebRequestCreate
WebRequest
和WebResponse
。见下文。我的示例生成失败的请求(通过抛出WebException
),但应该能够调整它以发送“真实”响应:
class WebRequestFailedCreate : IWebRequestCreate {
HttpStatusCode status;
String statusDescription;
public WebRequestFailedCreate(HttpStatusCode hsc, String sd) {
status = hsc;
statusDescription = sd;
}
#region IWebRequestCreate Members
public WebRequest Create(Uri uri) {
return new WebRequestFailed(uri, status, statusDescription);
}
#endregion
}
class WebRequestFailed : WebRequest {
HttpStatusCode status;
String statusDescription;
Uri itemUri;
public WebRequestFailed(Uri uri, HttpStatusCode status, String statusDescription) {
this.itemUri = uri;
this.status = status;
this.statusDescription = statusDescription;
}
WebException GetException() {
SerializationInfo si = new SerializationInfo(typeof(HttpWebResponse), new System.Runtime.Serialization.FormatterConverter());
StreamingContext sc = new StreamingContext();
WebHeaderCollection headers = new WebHeaderCollection();
si.AddValue("m_HttpResponseHeaders", headers);
si.AddValue("m_Uri", itemUri);
si.AddValue("m_Certificate", null);
si.AddValue("m_Version", HttpVersion.Version11);
si.AddValue("m_StatusCode", status);
si.AddValue("m_ContentLength", 0);
si.AddValue("m_Verb", "GET");
si.AddValue("m_StatusDescription", statusDescription);
si.AddValue("m_MediaType", null);
WebResponseFailed wr = new WebResponseFailed(si, sc);
Exception inner = new Exception(statusDescription);
return new WebException("This request failed", inner, WebExceptionStatus.ProtocolError, wr);
}
public override WebResponse GetResponse() {
throw GetException();
}
public override IAsyncResult BeginGetResponse(AsyncCallback callback, object state) {
Task<WebResponse> f = Task<WebResponse>.Factory.StartNew (
_ =>
{
throw GetException();
},
state
);
if (callback != null) f.ContinueWith((res) => callback(f));
return f;
}
public override WebResponse EndGetResponse(IAsyncResult asyncResult) {
return ((Task<WebResponse>)asyncResult).Result;
}
}
class WebResponseFailed : HttpWebResponse {
public WebResponseFailed(SerializationInfo serializationInfo, StreamingContext streamingContext)
: base(serializationInfo, streamingContext) {
}
}
您必须创建一个HttpWebResponse
子类,因为您无法创建一个子类。
棘手的部分(在GetException()
方法中)正在输入您无法覆盖的值,例如StatusCode
这就是我们最好的伙伴SerializaionInfo
进来的地方!这是您提供无法覆盖的值的地方。显然,覆盖你能够完成的部分(HttpWebResponse
),以便完成其余部分。
我如何获得所有AddValue()
次来电中的“姓名”?从异常消息!很高兴能够依次告诉我每个人,直到我开心。
现在,编译器会抱怨“过时”,但这仍然有效,包括.NET Framework第4版。
这是一个(传递)测试用例供参考:
[TestMethod, ExpectedException(typeof(WebException))]
public void WebRequestFailedThrowsWebException() {
string TestURIProtocol = TestContext.TestName;
var ResourcesBaseURL = TestURIProtocol + "://resources/";
var ContainerBaseURL = ResourcesBaseURL + "container" + "/";
WebRequest.RegisterPrefix(TestURIProtocol, new WebRequestFailedCreate(HttpStatusCode.InternalServerError, "This request failed on purpose."));
WebRequest wr = WebRequest.Create(ContainerBaseURL);
try {
WebResponse wrsp = wr.GetResponse();
using (wrsp) {
Assert.Fail("WebRequest.GetResponse() Should not have succeeded.");
}
}
catch (WebException we) {
Assert.IsInstanceOfType(we.Response, typeof(HttpWebResponse));
Assert.AreEqual(HttpStatusCode.InternalServerError, (we.Response as HttpWebResponse).StatusCode, "Status Code failed");
throw we;
}
}
答案 2 :(得分:3)
你做不到。最好的办法是将它包装在代理对象中,然后模拟它。或者,您必须使用可以拦截无法模拟的类型的模拟框架,例如TypeMock。但是你在谈论雄鹿。最好做一点包装。
显然你可以一点额外的工作。查看最高投票答案。
答案 3 :(得分:2)
我之前发现了以下博客,它解释了使用Microsoft Moles的一个很好的方法。
http://maraboustork.co.uk/index.php/2011/03/mocking-httpwebresponse-with-moles/
简而言之,解决方案建议如下:
[TestMethod]
[HostType("Moles")]
[Description("Tests that the default scraper returns the correct result")]
public void Scrape_KnownUrl_ReturnsExpectedValue()
{
var mockedWebResponse = new MHttpWebResponse();
MHttpWebRequest.AllInstances.GetResponse = (x) =>
{
return mockedWebResponse;
};
mockedWebResponse.StatusCodeGet = () => { return HttpStatusCode.OK; };
mockedWebResponse.ResponseUriGet = () => { return new Uri("http://www.google.co.uk/someRedirect.aspx"); };
mockedWebResponse.ContentTypeGet = () => { return "testHttpResponse"; };
var mockedResponse = "<html> \r\n" +
" <head></head> \r\n" +
" <body> \r\n" +
" <h1>Hello World</h1> \r\n" +
" </body> \r\n" +
"</html>";
var s = new MemoryStream();
var sw = new StreamWriter(s);
sw.Write(mockedResponse);
sw.Flush();
s.Seek(0, SeekOrigin.Begin);
mockedWebResponse.GetResponseStream = () => s;
var scraper = new DefaultScraper();
var retVal = scraper.Scrape("http://www.google.co.uk");
Assert.AreEqual(mockedResponse, retVal.Content, "Should have returned the test html response");
Assert.AreEqual("http://www.google.co.uk/someRedirect.aspx", retVal.FinalUrl, "The finalUrl does not correctly represent the redirection that took place.");
}
答案 4 :(得分:0)
这不是一个完美的解决方案,但它之前对我有用,值得特别注意简单:
同样是typemock forums中记录的类型模型示例:
using System;
using System.IO;
using System.Net;
using NUnit.Framework;
using TypeMock;
namespace MockHttpWebRequest
{
public class LibraryClass
{
public string GetGoogleHomePage()
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://www.google.com");
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
using (StreamReader reader = new StreamReader(response.GetResponseStream()))
{
return reader.ReadToEnd();
}
}
}
[TestFixture]
[VerifyMocks]
public class UnitTests
{
private Stream responseStream = null;
private const string ExpectedResponseContent = "Content from mocked response.";
[SetUp]
public void SetUp()
{
System.Text.UTF8Encoding encoding = new System.Text.UTF8Encoding();
byte[] contentAsBytes = encoding.GetBytes(ExpectedResponseContent);
this.responseStream = new MemoryStream();
this.responseStream.Write(contentAsBytes, 0, contentAsBytes.Length);
this.responseStream.Position = 0;
}
[TearDown]
public void TearDown()
{
if (responseStream != null)
{
responseStream.Dispose();
responseStream = null;
}
}
[Test(Description = "Mocks a web request using natural mocks.")]
public void NaturalMocks()
{
HttpWebRequest mockRequest = RecorderManager.CreateMockedObject<HttpWebRequest>(Constructor.Mocked);
HttpWebResponse mockResponse = RecorderManager.CreateMockedObject<HttpWebResponse>(Constructor.Mocked);
using (RecordExpectations recorder = RecorderManager.StartRecording())
{
WebRequest.Create("http://www.google.com");
recorder.CheckArguments();
recorder.Return(mockRequest);
mockRequest.GetResponse();
recorder.Return(mockResponse);
mockResponse.GetResponseStream();
recorder.Return(this.responseStream);
}
LibraryClass testObject = new LibraryClass();
string result = testObject.GetGoogleHomePage();
Assert.AreEqual(ExpectedResponseContent, result);
}
[Test(Description = "Mocks a web request using reflective mocks.")]
public void ReflectiveMocks()
{
Mock<HttpWebRequest> mockRequest = MockManager.Mock<HttpWebRequest>(Constructor.Mocked);
MockObject<HttpWebResponse> mockResponse = MockManager.MockObject<HttpWebResponse>(Constructor.Mocked);
mockResponse.ExpectAndReturn("GetResponseStream", this.responseStream);
mockRequest.ExpectAndReturn("GetResponse", mockResponse.Object);
LibraryClass testObject = new LibraryClass();
string result = testObject.GetGoogleHomePage();
Assert.AreEqual(ExpectedResponseContent, result);
}
}
}