public void MessageApiTest_Preview()
        {
            var input = new PreviewTextInput()
            {
                Text = new PreviewTextInput.TextInfo()
                {
                    Content = "Test"
                },
                ToWXName = "mhpyxinxing"
            };
            var result = _weChatApi.Preview(input);

            if (!result.IsSuccess())
            {
                Assert.Fail("调用群发预览接口(微信号)失败,返回结果如下:" + result.DetailResult);
            }

            input.ToWXName = null;
            input.ToUser   = "******";
            result         = _weChatApi.Preview(input);
            if (!result.IsSuccess())
            {
                Assert.Fail("调用群发预览接口(OpenId)失败,返回结果如下:" + result.DetailResult);
            }


            //var img = new PreviewImageInput()
            //{
            //    Image = new PreviewImageInput.ImageInfo()
            //    {
            //        //MediaId=
            //    }
            //};

            //TODO:其他类型
        }