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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。

/// <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。

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);

        }
 
    }
}

posted on 2011-07-24 20:21  冠军  阅读(8212)  评论(6编辑  收藏  举报