未调用 Webclient UploadStringCompleted 事件答案

【问题标题】：Webclient UploadStringCompleted event not being called未调用 Webclient UploadStringCompleted 事件
【发布时间】：2014-10-07 05:36:22
【问题描述】：

我正在为我们开发的一些网络服务编写单元测试。我有一个 [TestMethod] 发布到 web 服务作为休息。效果很好，但它不会触发我创建的事件处理程序方法。通过调试，我注意到在执行测试方法后，事件处理程序正在获取排除器。它去测试清理。

有人遇到过这个问题吗？这是代码

 [TestMethod,TestCategory("WebServices")]
        public void ValidateWebServiceGetUserAuthToken()
        {
            string _jsonstringparams =
                "{ \"Password\": \"xxx\", \"UserId\": \"xxxx\"}";
            using (var _requestclient = new WebClient())
            {
                _requestclient.UploadStringCompleted += _requestclient_UploadStringCompleted;
                var _uri = String.Format("{0}?format=Json", _webservicesurl);
                _requestclient.Headers.Add(HttpRequestHeader.ContentType, "application/json");
                _requestclient.UploadStringAsync(new Uri(_uri), "POST", _jsonstringparams);
            }
    }

    void _requestclient_UploadStringCompleted(object sender, UploadStringCompletedEventArgs e)
    {
        if (e.Result != null)
        { 
            var _responsecontent = e.Result.ToString();
            Console.WriteLine(_responsecontent);
        }
        else 
        {
            Assert.IsNotNull(e.Error.Message, "Test Case Failed");
        }
    }

【问题讨论】：

标签： c# webclient

【解决方案1】：

问题在于 UploadStringAsync 返回 void（即，它是一劳永逸的）并且本身并不能让您检测到完成。

有几个选项。第一个选项（这是我推荐的选项）是改用 HttpClient 并使用 PostAsync 方法——你可以await。在这种情况下，我会这样做：

[TestMethod, TestCategory("WebServices")]
public async Task ValidateWebServiceGetUserAuthToken()
{
    string _jsonstringparams =
        "{ \"Password\": \"xxx\", \"UserId\": \"xxxx\"}";
    using (var httpClient = new HttpClient())
    {
        var _uri = String.Format("{0}?format=Json", _webservicesurl);
        var stringContent = new StringContent(_jsonstringparams);
        stringContent.Headers.ContentType = new MediaTypeHeaderValue("application/json"); 
        HttpResponseMessage response = await httpClient.PostAsync(_uri, stringContent);
        // Or whatever status code this service response with
        Assert.AreEqual(HttpStatusCode.Accepted, response.StatusCode);
        var responseText = await response.Content.ReadAsStringAsync();
        // TODO: something more specific to your needs
        Assert.IsTrue(!string.IsNullOrWhiteSpace(responseText));
    }
}

另一种选择是更改您的完整事件处理程序，以向您的测试发出上传已完成的信号，并在您的测试中等待事件发生。例如：

[TestMethod, TestCategory("WebServices")]
public void ValidateWebServiceGetUserAuthToken()
{
    string _jsonstringparams =
        "{ \"Password\": \"xxx\", \"UserId\": \"xxxx\"}";
    using (var _requestclient = new WebClient())
    {
        _requestclient.UploadStringCompleted += _requestclient_UploadStringCompleted;
        var _uri = String.Format("{0}?format=Json", _webservicesurl);
        _requestclient.Headers.Add(HttpRequestHeader.ContentType, "application/json");
        _requestclient.UploadStringAsync(new Uri(_uri), "POST", _jsonstringparams);
        completedEvent.WaitOne();
    }
}

private ManualResetEvent completedEvent = new ManualResetEvent(false);
void _requestclient_UploadStringCompleted(object sender, UploadStringCompletedEventArgs e)
{
    if (e.Result != null)
    {
        var _responsecontent = e.Result.ToString();
        Console.WriteLine(_responsecontent);
    }
    else
    {
        Assert.IsNotNull(e.Error.Message, "Test Case Failed");
    }
    completedEvent.Set();
}

【讨论】：

有效！谢谢你。两种方法都奏效了。我也在考虑 Async 方法，但没有想到 ManualResetEvent。感谢您的回复！

【解决方案2】：

除了上面的答案之外，我还添加了一个方法来支持 httpwebresponse，这样我就不必等待事件了。

public static AuthTokenResponse GetUserToken(string username, string password)
        {
            string _jsonstringparams =
                String.Format("{{ \"Password\": \"{0}\", \"UserId\": \"{1}\"}}", password, username);
            string _webservicesurl = ConfigurationManager.AppSettings["WebservicesUrl"];
            HttpWebRequest _requestclient = (HttpWebRequest)WebRequest.Create(String.Format("{0}?format=Json", _webservicesurl));
            _requestclient.ContentType = "application/json";
            _requestclient.Method = "POST";
            using (var streamWriter = new StreamWriter(_requestclient.GetRequestStream()))
            {
                streamWriter.Write(_jsonstringparams);
                streamWriter.Flush();
                streamWriter.Close();
                var httpResponse = (HttpWebResponse)_requestclient.GetResponse();
                using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
                {
                    _responsecontent = streamReader.ReadToEnd();
                }
                AuthTokenResponse _clienttoken = JsonConvert.DeserializeObject<AuthTokenResponse>(_responsecontent);
                return _clienttoken;
            }
        }

【讨论】：