public void WhenPathChangesTest()
        {
            //监控文件
            WhenPathChanges("~/c/a.txt", VirtualPathProvider.FileExists, s => VirtualPathProvider.CreateFile(s, stream => { }), VirtualPathProvider.DeleteFile,
                            s =>
            {
                var path = VirtualPathProvider.MapPath(s);
                File.WriteAllText(path, "Test");
            });
            //监控目录
            WhenPathChanges("~/c/a", VirtualPathProvider.DirectoryExists, VirtualPathProvider.CreateDirectory, VirtualPathProvider.DeleteDirectory, null);

            if (VirtualPathProvider.DirectoryExists("~/c"))
            {
                VirtualPathProvider.DeleteDirectory("~/c");
            }
        }