CODEWITHSUNDEEP
c#httpclientxunitfixtureshttpclientfactory
Ahmed Negm
Ahmed Negm

Reputation: 905

Mocking IHttpClientFactory - xUnit C#

I was trying to build a generic HTTP service in my project (c# with .net core 2.1), and I have done it as per the below snippet HttpService.

I also started using it by calling it from my business logic class which uses this generic PostAsync method to post an HTTP call to a 3rd party with a content in body. It works perfectly.

But, when I tried to test it, I failed! Actually when I tried debugging (testing mode), I get null response when the debugger comes to this line var result = await _httpService.PostAsync("https://test.com/api", content); in business class Processor even with fake objects and mocks, although it works normally in debugging mode without testing/mocking.

HTTP service:

public interface IHttpService
{
    Task<HttpResponseMessage> PostAsync(string requestUri, HttpContent content);
}

public class HttpService : IHttpService
{
    private readonly IHttpClientFactory _httpClientFactory;

    public HttpService(IHttpClientFactory httpClientFactory)
    {
        _httpClientFactory = httpClientFactory;
    }

    public async Task<HttpResponseMessage> PostAsync(string requestUri, HttpContent content)
    {
        var httpClient = _httpClientFactory.CreateClient();
        httpClient.Timeout = TimeSpan.FromSeconds(3);
        var response = await httpClient.PostAsync(requestUri, content).ConfigureAwait(false);
        response.EnsureSuccessStatusCode();

        return response;
    }
}

Business class:

public class Processor : IProcessor
{
    private readonly IHttpService _httpService;

    public Processor() { }

    public Processor(IHttpService httpService, IAppSettings appSettings)
    {
        _httpService = httpService;
    }

    public async Task<HttpResponseMessage> PostToVendor(Order order)
    {
        // Building content
        var json = JsonConvert.SerializeObject(order, Formatting.Indented);
        var content = new StringContent(json, Encoding.UTF8, "application/json");

        // HTTP POST
        var result = await _httpService.PostAsync("https://test.com/api", content); // returns null during the test without stepping into the method PostAsyn itself

        return result;
    }
}

Test class:

public class MyTests
{
    private readonly Mock<IHttpService> _fakeHttpMessageHandler;
    private readonly IProcessor _processor; // contains business logic
    private readonly Fixture _fixture = new Fixture();

    public FunctionTest()
    {
        _fakeHttpMessageHandler = new Mock<IHttpService>();
        _processor = new Processor(_fakeHttpMessageHandler.Object);
    }

    [Fact]
    public async Task Post_To_Vendor_Should_Return_Valid_Response()
    {
        var fakeHttpResponseMessage = new Mock<HttpResponseMessage>(MockBehavior.Loose, new object[] { HttpStatusCode.OK });

        var responseModel = new ResponseModel
        {
            success = true,
            uuid = Guid.NewGuid().ToString()
        };

        fakeHttpResponseMessage.Object.Content = new StringContent(JsonConvert.SerializeObject(responseModel), Encoding.UTF8, "application/json");

        var fakeContent = _fixture.Build<DTO>().Create(); // DTO is the body which gonna be sent to the API
        var content = new StringContent(JsonConvert.SerializeObject(fakeContent), Encoding.UTF8, "application/json");

        _fakeHttpMessageHandler.Setup(x => x.PostAsync(It.IsAny<string>(), content))
            .Returns(Task.FromResult(fakeHttpResponseMessage.Object));

        var res = _processor.PostToVendor(fakeContent).Result;
        Assert.NotNull(res.Content);
        var actual = JsonConvert.SerializeObject(responseModel);
        var expected = await res.Content.ReadAsStringAsync();
        Assert.Equal(expected, actual);
    }
}

Upvotes: 2

Views: 893

Answers (1)

Uriil
Uriil

Reputation: 12628

Your problem is in mock set up:

_fakeHttpMessageHandler.Setup(x => x.PostAsync(It.IsAny<string>(), content))
        .Returns(Task.FromResult(fakeHttpResponseMessage.Object));

Second parameter for PostAsync method expected to be content, but since StringContent is a reference type, content you setup in mock is different from content you creating in processor. If you change it to next one, it should work as you expect:

    _fakeHttpMessageHandler.Setup(x => x.PostAsync(It.IsAny<string>(), It.IsAny<StringContent>()))
        .Returns(Task.FromResult(fakeHttpResponseMessage.Object));

P.S. null response to PostAsync means that method has default setup, which means that it will return default value

Upvotes: 3

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