I am dealing with a piece of code that looks like this:
public class Uploader : IUploader
{
public Uploader()
{
// assign member variables to dependency injected interface implementations
}
public async Task<string> Upload(string url, string data)
{
HttpResponseMessage result;
try
{
var handler = new HttpClientHandler();
var client = new HttpClient(handler);
result = await client.PostAsync(url, new FormUrlEncodedContent(data));
if (result.StatusCode != HttpStatusCode.OK)
{
return "Some Error Message";
}
else
{
return null; // Success!
}
}
catch (Exception ex)
{
// do some fancy stuff here
}
}
}
I am trying to unit test the Upload function. In particular, I need to mock the HttpClient. After reading the other answers on here and these two articles, I know that one of the better ways to solve this is to mock the HttpMessageHandler instead and pass that to HttpClient and have it return whatever I want.
So, I started along that path by first passing in HttpClient in the constructor as a dependency:
public class Uploader : IUploader
{
private readonly HttpClient m_httpClient; // made this a member variable
public Uploader(HttpClient httpClient) // dependency inject this
{
m_httpClient = httpClient;
}
public async Task<string> Upload(string url, string data)
{
HttpResponseMessage result;
try
{
var handler = new HttpClientHandler();
result = await m_httpClient.PostAsync(url, new FormUrlEncodedContent(data));
if (result.StatusCode != HttpStatusCode.OK)
{
return "Some Error Message";
}
else
{
return null; // Success!
}
}
catch (Exception ex)
{
// do some fancy stuff here
}
}
}
and adding: services.AddSingleton<HttpClient>(); to the ConfigureServices method of Startup.cs.
But now I face a slight issue where the original code specifically creates a HttpClientHandler to pass in. How then do I refactor that to take in a mockable handler?
I find the simplest way is to continue using HttpClient, but pass in a mocking HttpClientHandler such as https://github.com/richardszalay/mockhttp
Code sample from the link above:
var mockHttp = new MockHttpMessageHandler();
mockHttp.When("http://localhost/api/user/*")
.Respond("application/json", "{'name' : 'Test McGee'}");
// Inject the handler or client into your application code
var client = mockHttp.ToHttpClient();
var response = await client.GetAsync("http://localhost/api/user/1234");
var json = await response.Content.ReadAsStringAsync();
Console.Write(json); // {'name' : 'Test McGee'}
The Dependency Injection framework built into .NET Core ignores internal constructors, so it will call the parameter-less constructor in this scenario.
public sealed class Uploader : IUploader
{
private readonly HttpClient m_httpClient;
public Uploader() : this(new HttpClientHandler())
{
}
internal Uploader(HttpClientHandler handler)
{
m_httpClient = new HttpClient(handler);
}
// regular methods
}
In your unit tests, you can use the constructor accepting the HttpClientHandler:
[Fact]
public async Task ShouldDoSomethingAsync()
{
var mockHttp = new MockHttpMessageHandler();
mockHttp.When("http://myserver.com/upload")
.Respond("application/json", "{'status' : 'Success'}");
var uploader = new Uploader(mockHttp);
var result = await uploader.UploadAsync();
Assert.Equal("Success", result.Status);
}
Normally I'm not a big fan of having an internal constructor to facilitate testing, however, I find this more obvious and self-contained than registering a shared HttpClient.
HttpClientFactory might be another good option, but I haven't played around with that too much, so I'll just give info on what I've found useful myself.
One way would be to abstract your HTTP functionality into a service i.e. HttpService which implements an interface of IHttpService:
IHttpService
public interface IHttpService
{
Task<HttpResponseMessage> Post(Uri url, string payload, Dictionary<string, string> headers = null);
}
HttpService
public class HttpService : IHttpService
{
private static HttpClient _httpClient;
private const string MimeTypeApplicationJson = "application/json";
public HttpService()
{
_httpClient = new HttpClient();
}
private static async Task<HttpResponseMessage> HttpSendAsync(HttpMethod method, Uri url, string payload,
Dictionary<string, string> headers = null)
{
var request = new HttpRequestMessage(method, url);
request.Headers.Add("Accept", MimeTypeApplicationJson);
if (headers != null)
{
foreach (var header in headers)
{
request.Headers.Add(header.Key, header.Value);
}
}
if (!string.IsNullOrWhiteSpace(payload))
request.Content = new StringContent(payload, Encoding.UTF8, MimeTypeApplicationJson);
return await _httpClient.SendAsync(request);
}
public async Task<HttpResponseMessage> Post(Uri url, string payload, Dictionary<string, string> headers = null)
{
return await HttpSendAsync(HttpMethod.Post, url, payload, headers);
}
}
Add to your services:
services.AddSingleton<IHttpService, HttpService>();
In your class you would then inject IHttpService as a dependency:
public class Uploader : IUploader
{
private readonly IHttpService _httpService; // made this a member variable
public Uploader(IHttpService httpService) // dependency inject this
{
_httpService = httpService;
}
public async Task<string> Upload(string url, string data)
{
HttpResponseMessage result;
try
{
result = await _httpService.PostAsync(new Uri(url), data);
if (result.StatusCode != HttpStatusCode.OK)
{
return "Some Error Message";
}
else
{
return null; // Success!
}
}
catch (Exception ex)
{
// do some fancy stuff here
}
}
}
You could then use Moq to mock HttpService in your unit test:
[TestClass]
public class UploaderTests
{
private Mock<IHttpService> _mockHttpService = new Mock<IHttpService>();
[TestMethod]
public async Task WhenStatusCodeIsNot200Ok_ThenErrorMessageReturned()
{
// arrange
var uploader = new Uploader(_mockHttpService.Object);
var url = "someurl.co.uk";
var data = "data";
// need to setup your mock to return the response you want to test
_mockHttpService
.Setup(s => s.PostAsync(url, data))
.ReturnsAsync(new HttpResponseMessage(HttpStatusCode.InternalServerError));
// act
var result = await uploader.Upload(new Uri(url), data);
// assert
Assert.AreEqual("Some Error Message", result);
}
[TestMethod]
public async Task WhenStatusCodeIs200Ok_ThenNullReturned()
{
// arrange
var uploader = new Uploader(_mockHttpService.Object);
var url = "someurl.co.uk";
var data = "data";
// need to setup your mock to return the response you want to test
_mockHttpService
.Setup(s => s.PostAsync(new Uri(url), data))
.ReturnsAsync(new HttpResponseMessage(HttpStatusCode.OK));
// act
var result = await uploader.Upload(url, data);
// assert
Assert.AreEqual(null, result);
}
}
Related
I'm trying to pass a query string into a BaseAddress but it doesn't recognize the quotation mark "?".
The quotation breaks the URI
First I create my BaseAddress
httpClient.BaseAddress = new Uri($"https://api.openweathermap.org/data/2.5/weather?appid={Key}/");
Then I call the GetAsync method, trying to add another parameter
using (var response = await ApiHelper.httpClient.GetAsync("&q=mexico"))....
This is the URI the code is calling
https://api.openweathermap.org/data/2.5/&q=mexico
I'd be tempted to use a DelegatingHandler if you need to apply an API key to every single request:
private class KeyHandler : DelegatingHandler
{
private readonly string _escapedKey;
public KeyHandler(string key) : this(new HttpClientHandler(), key)
{
}
public KeyHandler(HttpMessageHandler innerHandler, string key) : base(innerHandler)
{
// escape the key since it might contain invalid characters
_escapedKey = Uri.EscapeDataString(key);
}
protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
// we'll use the UriBuilder to parse and modify the url
var uriBuilder = new UriBuilder(request.RequestUri);
// when the query string is empty, we simply want to set the appid query parameter
if (string.IsNullOrEmpty(uriBuilder.Query))
{
uriBuilder.Query = $"appid={_escapedKey}";
}
// otherwise we want to append it
else
{
uriBuilder.Query = $"{uriBuilder.Query}&appid={_escapedKey}";
}
// replace the uri in the request object
request.RequestUri = uriBuilder.Uri;
// make the request as normal
return base.SendAsync(request, cancellationToken);
}
}
Usage:
httpClient = new HttpClient(new KeyHandler(Key));
httpClient.BaseAddress = new Uri($"https://api.openweathermap.org/data/2.5/weather");
// since the logic of adding/appending the appid is done based on what's in
// the query string, you can simply write `?q=mexico` here, instead of `&q=mexico`
using (var response = await ApiHelper.httpClient.GetAsync("?q=mexico"))
** Note: If you're using ASP.NET Core, you should call services.AddHttpClient() and then use IHttpHandlerFactory to generate the inner handler for KeyHandler.
This is how I work around it:
Http client impl:
namespace StocksApi2.httpClients
{
public interface IAlphavantageClient
{
Task<string> GetSymboleDetailes(string queryToAppend);
}
public class AlphavantageClient : IAlphavantageClient
{
private readonly HttpClient _client;
public AlphavantageClient(HttpClient httpClient)
{
httpClient.BaseAddress = new Uri("https://www.alphavantage.co/query?apikey=<REPLACE WITH YOUR TOKEN>&");
httpClient.DefaultRequestHeaders.Add("Accept", "application/json; charset=utf-8");
httpClient.DefaultRequestHeaders.Add("User-Agent", "HttpClientFactory-Sample");
_client = httpClient;
}
public async Task<string> GetSymboleDetailes(string queryToAppend)
{
_client.BaseAddress = new Uri(_client.BaseAddress + queryToAppend);
return await _client.GetStringAsync("");
}
}
}
Controller:
namespace StocksApi2.Controllers
{
[ApiController]
[Route("api/[controller]")]
public class SymbolDetailsController : ControllerBase
{
private readonly IAlphavantageClient _client;
public SymbolDetailsController(IAlphavantageClient client)
{
_client = client;
}
[HttpGet]
public async Task<ActionResult> Get([FromQuery]string function = "TIME_SERIES_INTRADAY",
[FromQuery]string symbol = "MSFT", [FromQuery]string interval = "5min")
{
try {
string query = $"function={function}&symbol={symbol}&interval={interval}";
string result = await _client.GetSymboleDetailes(query);
return Ok(result);
}catch(Exception e)
{
return NotFound("Error: " + e);
}
}
}
}
And in Startup.cs inside ConfigureServices:
services.AddHttpClient();
services.AddHttpClient<IAlphavantageClient, AlphavantageClient>();
I have webapi where it needs to call some other endpoint and get data.
My current code as follows
//http client implementation
public interface IHttpClientFactory
{
HttpClient Create();
}
public class HttpClientFactory : IHttpClientFactory
{
private readonly ApplicationSettings _applicationSettings;
HttpClient _httpClient;
public HttpClientFactory(IOptions<ApplicationSettings> settings)
{
_applicationSettings = settings.Value;
}
public HttpClient Create()
{
if (_httpClient != null)
return _httpClient;
var client = new HttpClient()
{
BaseAddress = new Uri($"{_applicationSettings.BaseUrl}")
};
_httpClient = client;
return _httpClient;
}
}
public interface IGetItemsQuery
{
Task<IEnumerable<T>> Execute<T>(string url);
}
public class GetItemQuery: IGetItemsQuery
{
private readonly IHttpClientFactory _httpClientFactory;
public GetPhotosQuery(IHttpClientFactory httpClientFactory)
{
_httpClientFactory = httpClientFactory;
}
public async Task<IEnumerable<T>> Execute<T>(string url)
{
using (var response = await _httpClientFactory.Create().GetAsync($"{url}").ConfigureAwait(false))
{
response.EnsureSuccessStatusCode();
var resp = await response.Content.ReadAsStringAsync().ConfigureAwait(false);
var items = JArray.Parse(resp);
return items.ToObject<T[]>();
}
}
In my controller part
private readonly IGetItemsQuery _getItemsQuery;
public HomeController(IGetItemsQuery getItemsQuery)
{
_getItemsQuery = getItemsQuery;
}
appsettings
"ApplicationSettings": {
"BaseUrl": "http://someendpoint.com/"
}
Startup
services.Configure<ApplicationSettings>(Configuration.GetSection("ApplicationSettings"));
services.AddScoped<IGetItemsQuery, GetPhotosQuery>();
services.AddScoped<IHttpClientFactory, HttpClientFactory>();
I want to try something like below in my test
[Fact]
public void Test_Index()
{
// Arrange
var itemsQuery = new Mock<IGetItemsQuery>();
var controller = new HomeController(itemsQuery.Object);
// Act
var result = controller.Index();
// Assert
var viewResult = Assert.IsType<ViewResult>(result);
Assert.Null(viewResult.ViewName);
}
This is creating mock IGetItemsQuery but this isn't mocking the actual IHttpClientFactory.
Is there a way to do this
Based on your design with the abstracted dependencies there would be no need to mock a client factory in order to unit test the controller.
As you have done in your test, you mock IGetItemsQuery, but you have not set it up to behave as expected when invoked in the test.
If, for example, the controller method under test look something like this
private readonly IGetItemsQuery getItemsQuery;
public HomeController(IGetItemsQuery getItemsQuery) {
this.getItemsQuery = getItemsQuery;
}
public async Task<IActionResult> Index() {
var url = "....";
var items = await getItemsQuery.Execute<MyItem>(url);
return View(items);
}
Then an isolated unit test for the Index action as the method under test could look something like
[Fact]
public async Task Index_Should_Return_View_With_Items() {
// Arrange
var itemsQuery = new Mock<IGetItemsQuery>();
var items = new MyItem[] {
new MyItem(),
new MyItem()
};
itemsQuery.Setup(_ => _.Execute<MyItem>(It.IsAny<string>()))
.ReturnsAsync(items);
var controller = new HomeController(itemsQuery.Object);
// Act
var result = await controller.Index();
// Assert
var viewResult = Assert.IsType<ViewResult>(result);
Assert.Null(viewResult.ViewName);
}
So I have a controller that is using HttpClient to call a webservice like so:
public class DemoController : Controller
{
HttpClient client;
string baseUrl = "http://localhost:90/webservice";
public DemoController()
{
client = new HttpClient
{
BaseAddress = new Uri(baseUrl)
};
}
// GET: DemoInfo
public async Task<ActionResult> Index()
{
HttpResponseMessage response = await client.GetAsync(baseUrl + "vehicle/menu/year");
string content = "";
MenuItems result = null;
if (response.IsSuccessStatusCode)
{
content = await response.Content.ReadAsStringAsync();
result = (MenuItems)new XmlSerializer(typeof(MenuItems)).Deserialize(new StringReader(content));
}
return View("Index", result);
}
}
My unit test for this action is as follows:
[TestMethod]
public async Task Test_Index()
{
// Arrange
DemoController controller = new DemoController();
// Act
var result = await controller.Index();
ViewResult viewResult = (ViewResult) result;
// Assert
Assert.AreEqual("Index", viewResult.ViewName);
Assert.IsNotNull(viewResult.Model);
}
So obviously I would like to avoid making the web service call every time the test is run. Would I be on the right track in opting for an IoC container like Unity so that HttpClient would be injected into the controller? Is that overkill for what I'm trying to achieve? I'm aware that there is a lot of history with people struggling with properly mocking httpclient in there unit tests through this github issue. Any help would be greatly appreciated in giving some insight into how to write the controller to make a service call while still being testable.
All dependencies which makes tests slow should be abstracted.
Wrap HttpClient with an abstraction, which you can mock in your tests.
public interface IMyClient
{
Task<string> GetRawDataFrom(string url);
}
Then your controller will depend on that abstraction
public class DemoController : Controller
{
private readonly IMyClient _client;
private string _baseUrl = "http://localhost:90/webservice";
public DemoController(IMyClient client)
{
_client = client;
}
public async Task<ActionResult> Index()
{
var rawData = _client.GetRawDataFrom($"{_baseUrl}vehicle/menu/year");
using (var reader = new StringReader(rawData))
{
var result =
(MenuItems)new XmlSerializer(typeof(MenuItems)).Deserialize(reader);
return View("Index", result);
}
}
}
Then in tests you can mock your abstraction to return expected data
public class FakeClient : IMyClient
{
public string RawData { get; set; }
public Task<string> GetRawDataFrom(string url)
{
return Task.FromResult(RawData);
}
}
[TestMethod]
public async Task Test_Index()
{
// Arrange
var fakeClient = new FakeClient
{
RawData = #"[
{ Name: "One", Path: "/one" },
{ Name: "Two", Path: "/two" }
]"
};
DemoController controller = new DemoController(fakeClient);
// Act
var result = await controller.Index();
ViewResult viewResult = (ViewResult)result;
// Assert
Assert.AreEqual("Index", viewResult.ViewName);
Assert.IsNotNull(viewResult.Model);
}
Actual implementation will use HttpClient
public class MyHttpClient : IMyClient
{
public Task<string> GetRawDataFrom(string url)
{
var response = await client.GetAsync(url);
if (response.IsSuccessStatusCode)
{
return await response.Content.ReadAsStringAsync();
}
}
}
An alternative approach to testing HttpClient calls without service wrappers, mocks, or IoC containers is to use Flurl, a small wrapper library around HttpClient that provides (among other things) some robust testing features. [Disclaimer: I'm the author]
Here's what your controller would look like. There's a few ways to do this, but this approach uses string extension methods that abstract away the client entirely. (A single HttpClient instance per host is managed for you to prevent trouble.)
using Flurl.Http;
public class DemoController : Controller
{
string baseUrl = "http://localhost:90/webservice";
// GET: DemoInfo
public async Task<ActionResult> Index()
{
var content = await baseUrl
.AppendPathSegment("vehicle/menu/year")
.GetStringAsync();
var result = (MenuItems)new XmlSerializer(typeof(MenuItems)).Deserialize(new StringReader(content));
return View("Index", result);
}
}
And the test:
using Flurl.Http;
[TestMethod]
public async Task Test_Index()
{
// fake & record all HTTP calls in the test subject
using (var httpTest = new HttpTest())
{
// Arrange
httpTest.RespondWith(200, "<xml>some fake response xml...</xml>");
DemoController controller = new DemoController();
// Act
var result = await controller.Index();
ViewResult viewResult = (ViewResult) result;
// Assert
Assert.AreEqual("Index", viewResult.ViewName);
Assert.IsNotNull(viewResult.Model);
}
}
Flurl.Http is available on NuGet.
We have a few classes in our C# project that make calls out to 3rd party APIs. We're using HttpClient objects for the calls. We've set up our classes where we do these calls to accept an HttpClient so that when testing, we can use a custom/fake DelegatingHandler with the client.
We've set up our classes like this:
public class CallingService : ApiService
{
private readonly ISomeOtherService _someOtherService;
public CallingService (ILogger logger,
IConfigurationManager configurationManager,
ISomeOtherService someOtherService) : base(logger, configurationManager)
{
_someOtherService = someOtherService;
}
public CallingService (ILogger logger,
HttpClient client,
IConfigurationManager configurationManager,
ISomeOtherService someOtherService) : base(logger, configurationManager, client)
{
_someOtherService = someOtherService;
}
private async Task<XmlNodeList> TransmitToApi(string xml_string)
{
ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3 | SecurityProtocolType.Tls12;
//..
string type = "application/xml";
var content = new StreamContent(new MemoryStream(Encoding.ASCII.GetBytes(xml_string)));
var targetUri = new Uri(ConfigurationManager.GetAppSetting("ApiUrl"));
var message = new HttpRequestMessage
{
RequestUri = targetUri ,
Method = HttpMethod.Post,
Content = content
};
message.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("*/*"));
message.Content.Headers.Add("Content-Type", type);
message.Headers.Add("someHeader", someData);
HttpResponseMessage response = null;
try
{
// Define the cancellation token.
CancellationTokenSource source = new CancellationTokenSource();
CancellationToken token = source.Token;
response = await Client.SendAsync(message, token);
}
catch (Exception ex)
{
throw ex;
}
//...
return someData;
}
The base ApiService class defines a generic HttpClient object if one is not provided.
We're currently using SendAsync so we can define the message headers. (We have more headers than are listed here.)
The test defines the DelegatingHandler like this:
public class FakeResponseHandler : DelegatingHandler
{
private readonly Dictionary<Uri, HttpResponseMessage> _fakeResponses = new Dictionary<Uri, HttpResponseMessage>();
public void AddFakeResponse(Uri uri, HttpResponseMessage responseMessage, string content = "", bool asXml = false)
{
if (!string.IsNullOrWhiteSpace(content))
{
if (asXml)
{
responseMessage.Content = new StringContent(content, Encoding.UTF8, "application/xml");
}
else
{
responseMessage.Content = new StringContent(content, Encoding.UTF8, "application/json");
}
}
_fakeResponses.Add(uri, responseMessage);
}
protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
if (_fakeResponses.ContainsKey(request.RequestUri))
{
return _fakeResponses[request.RequestUri];
}
return new HttpResponseMessage(HttpStatusCode.NotFound) { RequestMessage = request };
}
}
And then:
[Fact]
public async Task ItWillDoStuffAndCallApi()
{
using (var mock = AutoMock.GetLoose())
{
mock.Mock<IConfigurationManager>()
.Setup(cm => cm.GetAppSetting("ApiUrl"))
.Returns("http://example.org/test/");
string testReturnData = GetFileContents("IntegrationTests.SampleData.SampleApiResponseXML.txt");
FakeResponseHandler fakeResponseHandler = new FakeResponseHandler();
fakeResponseHandler.AddFakeResponse(new Uri("http://example.org/test/"),
new HttpResponseMessage(HttpStatusCode.OK),
testReturnData,
true);
//HttpClient httpClient = new HttpClient(fakeResponseHandler);
HttpClient httpClient = HttpClientFactory.Create(fakeResponseHandler);
mock.Provide(httpClient);
var ourService = new CallingService();
ourService.TransmitToApi(someXmlString);
}
}
When we run the test, we receive the message:
Handler did not return a response message.
And we never seem to get into DelegatingHandler.SendAsync method.
We have other classes calling APIs using HttpClient.PostAsync or GetAsync, and these do call the DelegatingHandler.SendAsync method and work as expected.
We've tried:
HttpClient httpClient = new HttpClient(fakeResponseHandler);
and
HttpClient httpClient = HttpClientFactory.Create(fakeResponseHandler);
We've also tried Client.SendAsync with and without the cancellation token.
Why is this not working?
Should we re-write this to use PostAsync?
I'd need to see the implementation of HttpClientFactory.Create and what Client.SendAsync actually does internally but nevertheless I was able to use the sample code you provide and fill in the blanks where I could to get the following to work:
public class FakeResponseHandler : DelegatingHandler
{
private readonly Dictionary<Uri, HttpResponseMessage> _fakeResponses = new Dictionary<Uri, HttpResponseMessage>();
public void AddFakeResponse(Uri uri, HttpResponseMessage responseMessage, string content = "", bool asXml = false)
{
if (!string.IsNullOrWhiteSpace(content))
{
if (asXml)
{
responseMessage.Content = new StringContent(content, Encoding.UTF8, "application/xml");
}
else
{
responseMessage.Content = new StringContent(content, Encoding.UTF8, "application/json");
}
}
_fakeResponses.Add(uri, responseMessage);
}
protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
var emptyContent = string.Empty;
if (request.Content.Headers.ContentType.MediaType == "application/xml")
emptyContent = "<empty />";
return Task.FromResult(_fakeResponses.ContainsKey(request.RequestUri) ?
_fakeResponses[request.RequestUri] :
new HttpResponseMessage(HttpStatusCode.NotFound)
{
RequestMessage = request,
Content = new StringContent(emptyContent)
});
}
}
Just to make things clean use Task.FromResult to return a task in SendAsync and also provide an empty content to avoid null reference exceptions.
public class CallingService
{
private readonly HttpClient _httpClient;
private readonly IConfigurationManager _configurationManager;
public CallingService(HttpClient httpClient,
IConfigurationManager configurationManager)
{
_httpClient = httpClient;
_configurationManager = configurationManager;
}
public async Task<XmlNodeList> TransmitToApi(string xml_string)
{
ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3 | SecurityProtocolType.Tls12;
//..
string type = "application/xml";
var content = new StreamContent(new MemoryStream(Encoding.ASCII.GetBytes(xml_string)));
var targetUri = new Uri(_configurationManager.GetAppSetting("ApiUrl"));
var message = new HttpRequestMessage
{
RequestUri = targetUri,
Method = HttpMethod.Post,
Content = content
};
message.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("*/*"));
message.Content.Headers.Add("Content-Type", type);
string somedata;
try
{
// Define the cancellation token.
CancellationTokenSource source = new CancellationTokenSource();
CancellationToken token = source.Token;
var response = await _httpClient.SendAsync(message, token);
somedata = await response.Content.ReadAsStringAsync();
}
catch (Exception ex)
{
throw ex;
}
//...
var xmlDoc = new XmlDocument();
xmlDoc.LoadXml(somedata);
return xmlDoc.SelectNodes("*");
}
}
And then the test passes the instance of HttpClient to CallingService:
[TestMethod]
public async Task TestMethod1()
{
const string content = #"<root><test>1243</test></root>";
const string httpExample = "http://example.org/test/";
var configurationManager = new Mock<IConfigurationManager>();
configurationManager
.Setup(cm => cm.GetAppSetting("ApiUrl"))
.Returns(httpExample);
var fakeResponseHandler = new FakeResponseHandler();
fakeResponseHandler.AddFakeResponse(new Uri(httpExample),
new HttpResponseMessage(HttpStatusCode.OK), content, true);
using (var httpClient = new HttpClient(fakeResponseHandler))
{
var ourService = new CallingService(httpClient, configurationManager.Object);
var result = await ourService.TransmitToApi(content);
Assert.AreEqual(content, result.Item(0)?.OuterXml);
}
}
This all works so if I had to guess - the issue would be somewhere in your HttpClientFacotry.
Hope that helps!! Cheers, :)
The app I'm working on is supposed to retrieve a json string with the http client after which it gets deserialised and used in the app.
Everything works, except for the await functionality. I'm doing something wrong and I can't seem to figure out what. How can I make sure that my DataService class waits untill I have my json and it has been deserialized?
The DataService class:
class DataService : IDataService
{
private IEnumerable<Concert> _concerts;
public DataService()
{
_concerts = new DataFromAPI()._concerts;
Debug.WriteLine("____Deserialization should be done before continuing____");
**other tasks that need the json**
}
}
My http client class:
class DataFromAPI
{
public IEnumerable<Concert> _concerts { get; set; }
public DataFromAPI()
{
Retrieve();
}
public async Task Retrieve()
{
try
{
HttpClient client = new HttpClient();
HttpRequestMessage request = new HttpRequestMessage();
var result = await client.GetAsync(new Uri("http://url-of-my-api"), HttpCompletionOption.ResponseContentRead);
string jsonstring = await result.Content.ReadAsStringAsync();
DownloadCompleted(jsonstring);
}
catch {}
}
void DownloadCompleted(string response)
{
try
{
_concerts = JsonConvert.DeserializeObject<IEnumerable<Concert>>(response.ToString());
}
catch {}
}
}
solution
After a lot of trial and error I realised that for this particular thingy it didn't have to be async, so I just recreated is on the main thread, with success:
The DataService class:
class DataService : IDataService
{
private IEnumerable<Concert> _concerts;
public DataService()
{
_concerts = new DataFromAPI()._concerts;
}
}
My http client class:
public static class DataFromAPI
{
public void Retrieve()
{
try
{
HttpClient client = new HttpClient();
HttpRequestMessage request = new HttpRequestMessage();
var result = client.GetAsync("http://url-of-my-api").Result;
if (result.IsSuccessStatusCode)
{
var responseContent = result.Content;
}
DownloadCompleted(result.Content.ReadAsStringAsync().Result);
}
catch {}
}
}
You are calling Retrieve() without await in the DataFromAPI constructor, That's why your method isn't awaited.
You should better call this methods outside the constructor, with the await keyword like this :
await Retrieve();
You have to refactor your code a little. Here's an example :
public class DataService : IDataService
{
private IEnumerable<Concert> _concerts;
public async Task LoadData()
{
_concerts = await DataFromAPI.Retrieve();
**other tasks that need the json**
}
}
public static class DataFromAPI
{
public static async Task<IEnumerable<Concert>> Retrieve()
{
try
{
HttpClient client = new HttpClient();
HttpRequestMessage request = new HttpRequestMessage();
var result = await client.GetAsync(new Uri("http://url-of-my-api"), HttpCompletionOption.ResponseContentRead);
string jsonstring = await result.Content.ReadAsStringAsync();
return JsonConvert.DeserializeObject<IEnumerable<Concert>>(response.ToString());
}
catch(Exception)
{
}
return Enumerable.Empty<Concert>();
}
}
Then, when you create your DataService instance, just after you have to call it's LoadData() method.
DataService ds = new DataService();
await ds.LoadData();
And of course, these two lines of code must also be called from an async method. (async / await all the way)
After a lot of trial and error I realised that for this particular thingy it didn't have to be async, so I just recreated is on the main thread, with success:
The DataService class:
class DataService : IDataService
{
private IEnumerable<Concert> _concerts;
public DataService()
{
_concerts = new DataFromAPI()._concerts;
}
}
My http client class:
public static class DataFromAPI
{
public void Retrieve()
{
try
{
HttpClient client = new HttpClient();
HttpRequestMessage request = new HttpRequestMessage();
var result = client.GetAsync("http://url-of-my-api").Result;
if (result.IsSuccessStatusCode)
{
var responseContent = result.Content;
}
DownloadCompleted(result.Content.ReadAsStringAsync().Result);
}
catch {}
}
}