测试 MVC 之 Mock HttpContext

在 Web 中进行测试驱动的开发，比较大的困难是模拟 HttpContext ，它太复杂了。

moq 框架提供了强大的模拟能力，但是，模拟一个 HttpContext 对象还是需要自己来动手。

为此，我自己写了一个方法来完成这个工作。其中，还顺便使用 Log4Net 来输出一下它的工作情况。

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/// <summary> /// 创建上下文模拟对象 /// 至少需要支持 ///     Request 中 ///         AppRelativeCurrentExecutionFilePath， ///         ApplicationPath ///         PathInfo ///     Response 中 ///         ApplyAppPathModifier /// </summary> /// <returns></returns> private Moq.Mock<System.Web.HttpContextBase> CreateHttpContext() {     log4net.ILog log = log4net.LogManager.GetLogger("CreateHttpContext");       string ApplicationPath = "/";     string PathInfo = "";     string AppRelativeCurrentExecutionFilePath = "~/";       var contextMock = new Moq.Mock<System.Web.HttpContextBase>();       contextMock         .Setup(c => c.Request.AppRelativeCurrentExecutionFilePath)         .Returns(AppRelativeCurrentExecutionFilePath)         .Callback(() => log.Info("Calling AppRelativeCurrentExecutionFilePath"));       contextMock         .Setup(c => c.Request.ApplicationPath)         .Returns(ApplicationPath)         .Callback(() => log.Info("Calling ApplicationPath"));     contextMock.Setup(rc => rc.Request.PathInfo)         .Returns(PathInfo)         .Callback(() => log.Info("Calling PathInfo"));       contextMock         .Setup(rc => rc.Response.ApplyAppPathModifier(Moq.It.IsAny<string>()))         .Returns((string s) => s)         .Callback((string s) => log.InfoFormat("Calling ApplyAppPathModifier: {0}.", s));       return contextMock; }

虽然这个方法已经能够完成我需要的测试，但是，我希望能将它提炼一下，得到一个更加通用的 Mock 方法。

很快，我发现这个工作已经在很久以前被 Scott Hanselman 介绍过一次了，其中甚至还写了不同的 Mock 框架下的提供方法。不过 moq 版本的作者不是他，而是另外一个人 Daniel Cazzulino， 这篇文章你可以在这里找到：http://www.hanselman.com/blog/ASPNETMVCSessionAtMix08TDDAndMvcMockHelpers.aspx，还可以顺便看一下 Daniel Cazzulino 的博客：http://blogs.clariusconsulting.net/kzu/

不过，他的文章是在 2008 年写的，实在太古老了。当时还是 MVC 的 Preview2 ，moq 在那个时候就已经诞生了，看来我太孤陋寡闻了。

回到我们的主题，经过了这么长的时间，moq 已经有了一些变化，使用最新的 moq 语法修改之后，发现他的的代码没有能够通过测试。

与我的比较一下，发现其中少了对 Response 中 ApplyAppPathModifier 方法的支持，增加之后就正常了。

下面是修改之后的代码，希望能给你带来方便。

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using System; using System.Web; using System.Text.RegularExpressions; using System.IO; using System.Collections.Specialized; using System.Web.Mvc; using System.Web.Routing;   using Moq;   namespace UnitTests {     public static class MvcMockHelpers     {         public static HttpContextBase FakeHttpContext()         {             var context = new Mock<HttpContextBase>();             var request = new Mock<HttpRequestBase>();             var response = new Mock<HttpResponseBase>();             var session = new Mock<HttpSessionStateBase>();             var server = new Mock<HttpServerUtilityBase>();               // 必须要设置 Response 的 ApplyAppPathModifier 方法支持             response                 .Setup(rsp => rsp.ApplyAppPathModifier(Moq.It.IsAny<string>()))                 .Returns((string s) => s);                               context.Setup(ctx => ctx.Request).Returns(request.Object);             context.Setup(ctx => ctx.Response).Returns(response.Object);             context.Setup(ctx => ctx.Session).Returns(session.Object);             context.Setup(ctx => ctx.Server).Returns(server.Object);               return context.Object;         }           public static HttpContextBase FakeHttpContext(string url)         {             HttpContextBase context = FakeHttpContext();             context.Request.SetupRequestUrl(url);             return context;         }           // Controller 的一个扩展方法         public static void SetFakeControllerContext(this Controller controller)         {             var httpContext = FakeHttpContext();             ControllerContext context = new ControllerContext(new RequestContext(httpContext, new RouteData()), controller);             controller.ControllerContext = context;         }           static string GetUrlFileName(string url)         {             if (url.Contains("?"))                 return url.Substring(0, url.IndexOf("?"));             else                 return url;         }           static NameValueCollection GetQueryStringParameters(string url)         {             if (url.Contains("?"))             {                 NameValueCollection parameters = new NameValueCollection();                   string[] parts = url.Split("?".ToCharArray());                 string[] keys = parts[1].Split("&".ToCharArray());                   foreach (string key in keys)                 {                     string[] part = key.Split("=".ToCharArray());                     parameters.Add(part[0], part[1]);                 }                   return parameters;             }             else             {                 return null;             }         }           // 扩展 HttpRequestBase         public static void SetHttpMethodResult(this HttpRequestBase request, string httpMethod)         {             Mock.Get(request)                 .Setup(req => req.HttpMethod)                 .Returns(httpMethod);         }           // 设置请求的地址         public static void SetupRequestUrl(this HttpRequestBase request, string url)         {             log4net.ILog log = log4net.LogManager.GetLogger("CreateHttpContext");               if (url == null)                 throw new ArgumentNullException("url");               if (!url.StartsWith("~/"))                 throw new ArgumentException("Sorry, we expect a virtual url starting with \"~/\".");               var mock = Mock.Get(request);               mock.Setup(req => req.QueryString)                 .Returns(GetQueryStringParameters(url));             mock.Setup(req => req.AppRelativeCurrentExecutionFilePath)                 .Returns(GetUrlFileName(url))                 .Callback(() => log.Info("Calling AppRelativeCurrentExecutionFilePath"));                 mock.Setup(req => req.PathInfo)                 .Returns(string.Empty);           }        } }