NopCmmerce的FakeHttpContext类

在 Web 中进行测试驱动的开发，比较大的困难是模拟 HttpContext;

1.Nop提供了完整的FakeHttpContext实现，如图

1.FakeHttpContext的作用。

控制器进行单元测试时模拟web上下文环境，还有一些其他对HttpContext有依赖的组件也可以使用Fake从而进行组件的单元测试。

2.例举Nop中使用到FakeHttpContext的地方

(1).NopEngine(初始化NopEngine时，是web环境就注册真实HttpContext，否则注册FakeHttpContext)

//HTTP context and other related stuff
            builder.Register(c => 
                //register FakeHttpContext when HttpContext is not available
                HttpContext.Current != null ?
                (new HttpContextWrapper(HttpContext.Current) as HttpContextBase) :
                (new FakeHttpContext("~/") as HttpContextBase))
                .As<HttpContextBase>()
                .InstancePerHttpRequest();
            builder.Register(c => c.Resolve<HttpContextBase>().Request)
                .As<HttpRequestBase>()
                .InstancePerHttpRequest();
            builder.Register(c => c.Resolve<HttpContextBase>().Response)
                .As<HttpResponseBase>()
                .InstancePerHttpRequest();
            builder.Register(c => c.Resolve<HttpContextBase>().Server)
                .As<HttpServerUtilityBase>()
                .InstancePerHttpRequest();
            builder.Register(c => c.Resolve<HttpContextBase>().Session)
                .As<HttpSessionStateBase>()
                .InstancePerHttpRequest();

(2)RoutesTests( Route依赖HttpContextBase，可以用Fake类代替 )

[Test]
        public void Blog_routes()
        {
            //TODO why does it pass null instead of "new BlogPagingFilteringModel()" as it's done in real application? The same is about issue is in the other route test methods
            "~/blog/".ShouldMapTo<BlogController>(c => c.List(null));
            "~/blog/rss/1".ShouldMapTo<BlogController>(c => c.ListRss(1));
            "~/blog/2/".ShouldMapTo<BlogController>(c => c.BlogPost(2));
            "~/blog/2/test-se-name".ShouldMapTo<BlogController>(c => c.BlogPost(2));
            //TODO validate properties such as 'Tag' or 'Month' in the passed BlogPagingFilteringModel. The same is about issue is in the other route test methods
            //"~/blog/tag/sometag".ShouldMapTo<BlogController>(c => c.List(new BlogPagingFilteringModel() { Tag = "sometag" }));
            //"~/blog/month/3".ShouldMapTo<BlogController>(c => c.List(new BlogPagingFilteringModel() { Month = "4" }));
        }

(3)其他组件，如WebHelperTests，AdminAuthorizeAttributeTests都依赖了HttpContextBase

总结：这些Fake类为单元测试提供了模拟的Web上下文环境。，再也不用担心控制器以及类库因为用了HttpContextBase（最常见的包括Session，Request，Response）而变得难以进行单元测试了（但在控制器中还是应该尽量少用这些）