public async Task TestPayAsync_1()
        {
            //设置
            Id.SetId("nonce");
            Web.SetIp("ip");
            _service = new WechatpayAppPayService(new WechatpayConfigProvider(new WechatpayConfig {
                AppId      = "a",
                MerchantId = "m",
                PrivateKey = "p",
                NotifyUrl  = "n"
            }));

            //结果
            String expected = new String();

            expected.Append("<xml>");
            expected.Append("<appid><![CDATA[a]]></appid>");
            expected.Append("<body><![CDATA[b]]></body>");
            expected.Append("<mch_id><![CDATA[m]]></mch_id>");
            expected.Append("<nonce_str><![CDATA[nonce]]></nonce_str>");
            expected.Append("<notify_url><![CDATA[n]]></notify_url>");
            expected.Append("<out_trade_no><![CDATA[o]]></out_trade_no>");
            expected.Append("<sign><![CDATA[1EA6032990E252DF1E0301E20B93950A]]></sign>");
            expected.Append("<sign_type><![CDATA[MD5]]></sign_type>");
            expected.Append("<spbill_create_ip><![CDATA[ip]]></spbill_create_ip>");
            expected.Append("<total_fee>1023</total_fee>");
            expected.Append("<trade_type><![CDATA[APP]]></trade_type>");
            expected.Append("</xml>");

            //执行
            _service.IsSend = false;
            var result = await _service.PayAsync(new PayParam {
                Subject = "b",
                Money   = 10.23M,
                OrderId = "o"
            });

            //输出
            _output.WriteLine($"Parameter:{result.Parameter}");

            //验证
            Assert.Equal(expected.ToString(), result.Parameter);
        }
 /// <summary>
 /// 测试初始化
 /// </summary>
 public WechatpayAppPayServiceTest(ITestOutputHelper output)
 {
     _output  = output;
     _service = new WechatpayAppPayService(new TestConfigProvider());
 }