Como faço para testar o método de ação da API da Web quando ele retorna IHttpActionResult?

Vamos assumir que este é o meu método de ação

public IHttpActionResult Get(int id)
{
    var status = GetSomething(id);
    if (status)
    {
        return Ok();
    }
    else
    {
        return NotFound();
    }
}

O teste será

var httpActionResult = controller.Get(1);

Como verifico meu código de status http depois disso?

Aqui Ok()está apenas um auxiliar para o tipo OkResultque define o status da resposta como HttpStatusCode.Ok... para que você possa apenas verificar se a instância do resultado da sua ação é um OkResult... alguns exemplos (escritos em XUnit):

// if your action returns: NotFound()
IHttpActionResult actionResult = valuesController.Get(10);
Assert.IsType<NotFoundResult>(actionResult);

// if your action returns: Ok()
actionResult = valuesController.Get(11);
Assert.IsType<OkResult>(actionResult);

// if your action was returning data in the body like: Ok<string>("data: 12")
actionResult = valuesController.Get(12);
OkNegotiatedContentResult<string> conNegResult = Assert.IsType<OkNegotiatedContentResult<string>>(actionResult);
Assert.Equal("data: 12", conNegResult.Content);

// if your action was returning data in the body like: Content<string>(HttpStatusCode.Accepted, "some updated data");
actionResult = valuesController.Get(13);
NegotiatedContentResult<string> negResult = Assert.IsType<NegotiatedContentResult<string>>(actionResult);
Assert.Equal(HttpStatusCode.Accepted, negResult.StatusCode);
Assert.Equal("some updated data", negResult.Content);

Hora de ressuscitar uma pergunta morta

As respostas atuais dependem da conversão do objeto de resposta para um tipo conhecido. Infelizmente, as respostas não parecem ter uma hierarquia utilizável ou caminho de conversão implícito para que isso funcione sem um conhecimento íntimo da implementação do controlador. Considere o seguinte:

public class MixedCodeStandardController : ApiController {

    public readonly object _data = new Object();

    public IHttpActionResult Get() {
        return Ok(_data);
    }

    public IHttpActionResult Get(int id) {
        return Content(HttpStatusCode.Success, _data);
    }
}

Testando a classe:

var testController = new MixedCodeStandardController();

var getResult = testController.Get();
var posRes = getResult as OkNegotiatedContentResult<object>;
Assert.IsType<OkNegotiatedContentResult<object>>(getResult);
Assert.AreEqual(HttpStatusCode.Success, posRes.StatusCode);
Assert.AreEqual(testController._data, posRes.Content);

var idResult = testController.Get(1);
var oddRes = getResult as OkNegotiatedContentResult<object>; // oddRes is null
Assert.IsType<OkNegotiatedContentResult<object>>(idResult); // throws failed assertion
Assert.AreEqual(HttpStatusCode.Success, oddRes.StatusCode); // throws for null ref
Assert.AreEqual(testController._data, oddRes.Content); // throws for null ref

Fora da caixa preta, o fluxo de resposta é essencialmente o mesmo. O teste deve saber como o controlador implementou a chamada de retorno para testá-la dessa maneira.

Em vez disso, use o objeto HttpResponseMessage do IHttpActionResult retornado. Isso garante que o teste possa ser consistente, mesmo quando o código do controlador não for:

var testController = new MixedCodeStandardController();

var getResult = testController.Get();
var getResponse = getResult.ExecuteAsync(CancellationToken.None).Result;
Assert.IsTrue(getResponse.IsSuccessStatusCode);
Assert.AreEqual(HttpStatusCode.Success, getResponse.StatusCode);

var idResult = testController.Get(1);
var idResponse = idResult.ExecuteAsync(CancellationToken.None).Result;
Assert.IsTrue(idResponse.IsSuccessStatusCode);
Assert.AreEqual(HttpStatusCode.Success, idResponse.StatusCode);

Esta é a resposta aceita por Kiran Challa, adaptada para NUnit;

var valuesController = controller;
// if your action returns: NotFound()
IHttpActionResult actionResult = valuesController.Get(10);
var notFoundRes = actionResult as NotFoundResult;
Assert.IsNotNull(notFoundRes);

// if your action returns: Ok()
actionResult = valuesController.Get(11);
var posRes = actionResult as OkResult;
Assert.IsNotNull(posRes);

// if your action was returning data in the body like: Ok<string>("data: 12")
actionResult = valuesController.Get(12);
var conNegResult = actionResult as OkNegotiatedContentResult<string>;
Assert.IsNotNull(conNegResult);
Assert.AreEqual("data: 12", conNegResult.Content);

// if your action was returning data in the body like: Content<string>(HttpStatusCode.Accepted, "some updated data");
actionResult = valuesController.Get(13);
var negResult = actionResult as NegotiatedContentResult<string>;
Assert.IsNotNull(negResult);
Assert.AreEqual(HttpStatusCode.Accepted, negResult.StatusCode);
Assert.AreEqual("some updated data", negResult.Content);

https://docs.microsoft.com/pt-br/aspnet/web-api/overview/testing-and-debugging/unit-testing-controllers-in-web-api#testing-actions-that-return-ihttpactionresult

Assert.IsInstanceOfType (httpActionResult, typeof (OkResult));

Se IHttpActionResult contiver um objeto JSON, por exemplo, {"token": "A"}, podemos usar o seguinte código.

        var result = usercontroller.GetLogin("user", "password");
        Assert.IsInstanceOfType(result, typeof(OkNegotiatedContentResult<Dictionary<string,string>>));
        var content = result as OkNegotiatedContentResult<Dictionary<string, string> >;
        Assert.AreEqual("A", content.Content["token"]);

Após algumas horas de pesquisa e tentativas, finalmente descobri como testar completamente meus métodos da API da Web 2 que retornam IHttpActionResulte usam o middleware OWIN e a implementação padrão do ASP.NET Identity.

Vou testar o Get()método da seguinte maneira ApiController:

public class AccountController : ApiController
{
    private ApplicationUserManager _userManager;
    public ApplicationUserManager UserManager => _userManager ?? HttpContext.Current.GetOwinContext().GetUserManager<ApplicationUserManager>();

    [Route("api/account"), HttpGet]
    public async Task<IHttpActionResult> Get()
    {
        var user = await UserManager.FindByIdAsync(User.Identity.GetUserId());
        if (user == null)
        {
            ModelState.AddModelError(ModelStateConstants.Errors, "Account not found! Try logging out and in again.");
            return BadRequest(ModelState);
        }

        var roles = await UserManager.GetRolesAsync(user.Id);

        var accountModel = new AccountViewModel
        {
            FullName = user.FullName,
            Email = user.Email,
            Phone = user.PhoneNumber,
            Organization = user.Organization.Name,
            Role = string.Join(", ", roles)
        };

        return Ok(accountModel);
    }

    protected override void Dispose(bool disposing)
    {
        if (disposing)
        {
            if (_userManager != null)
            {
                _userManager.Dispose();
                _userManager = null;
            }
        }

        base.Dispose(disposing);
    }
}

Comece com uma classe base da qual todas as classes de teste herdarão:

public class BaseTest
{
    protected static User CurrentUser;
    protected static IList<string> Roles;

    public BaseTest()
    {
        var email = "unit@test.com";

        CurrentUser = new User
        {
            FullName = "Unit Tester",
            Email = email,
            UserName = email,
            PhoneNumber = "123456",
            Organization = new Organization
            {
                Name = "Test Organization"
            }
        };

        Roles = new List<string>
        {
            "Administrator"
        };
    }

    protected void InitializeApiController(ApiController apiController)
    {
        //Init fake controller Http and Identity data
        var config = new HttpConfiguration();
        var request = new HttpRequestMessage();
        var routeData = new HttpRouteData(new HttpRoute(""));
        apiController.ControllerContext = new HttpControllerContext(config, routeData, request)
        {
            Configuration = config
        };

        apiController.User = new GenericPrincipal(new GenericIdentity(""), new[] { "" });

        //Initialize Mocks
        var appUserMgrMock = GetMockedApplicationUserManager();
        var appSignInMgr = GetMockedApplicationSignInManager(appUserMgrMock);
        var appDbContext = GetMockedApplicationDbContext();

        //Configure HttpContext.Current.GetOwinContext to return mocks
        var owin = new OwinContext();
        owin.Set(appUserMgrMock.Object);
        owin.Set(appSignInMgr.Object);
        owin.Set(appDbContext.Object);

        HttpContext.Current = new HttpContext(new HttpRequest(null, "http://test.com", null), new HttpResponse(null));
        HttpContext.Current.Items["owin.Environment"] = owin.Environment;
    }

    private static Mock<ApplicationSignInManager> GetMockedApplicationSignInManager(Mock<ApplicationUserManager> appUserMgrMock)
    {
        var authMgr = new Mock<Microsoft.Owin.Security.IAuthenticationManager>();
        var appSignInMgr = new Mock<ApplicationSignInManager>(appUserMgrMock.Object, authMgr.Object);

        return appSignInMgr;
    }

    private Mock<ApplicationUserManager> GetMockedApplicationUserManager()
    {
        var userStore = new Mock<IUserStore<User>>();
        var appUserMgr = new Mock<ApplicationUserManager>(userStore.Object);
        appUserMgr.Setup(aum => aum.FindByIdAsync(It.IsAny<string>())).ReturnsAsync(CurrentUser);
        appUserMgr.Setup(aum => aum.GetRolesAsync(It.IsAny<string>())).ReturnsAsync(Roles);

        return appUserMgr;
    }

    private static Mock<ApplicationDbContext> GetMockedApplicationDbContext()
    {
        var dbContext = new Mock<ApplicationDbContext>();
        dbContext.Setup(dbc => dbc.Users).Returns(MockedUsersDbSet);

        return dbContext;
    }

    private static IDbSet<User> MockedUsersDbSet()
    {
        var users = new List<User>
        {
            CurrentUser,
            new User
            {
                FullName = "Testguy #1",
                Email = "test@guy1.com",
                UserName = "test@guy1.com",
                PhoneNumber = "123456",
                Organization = new Organization
                {
                    Name = "Test Organization"
                }
            }
        }.AsQueryable();

        var usersMock = new Mock<DbSet<User>>();
        usersMock.As<IQueryable<User>>().Setup(m => m.Provider).Returns(users.Provider);
        usersMock.As<IQueryable<User>>().Setup(m => m.Expression).Returns(users.Expression);
        usersMock.As<IQueryable<User>>().Setup(m => m.ElementType).Returns(users.ElementType);
        usersMock.As<IQueryable<User>>().Setup(m => m.GetEnumerator()).Returns(users.GetEnumerator);

        return usersMock.Object;
    }
}

O InitializeApiControllermétodo contém carne e batatas.

Agora podemos escrever nossos testes para AccountController:

public class AccountControllerTests : BaseTest
{
    private readonly AccountController _accountController;

    public AccountControllerTests()
    {
        _accountController = new AccountController();
        InitializeApiController(_accountController);
    }

    [Test]
    public async Task GetShouldReturnOk()
    {
        var result = await _accountController.Get();
        var response = await result.ExecuteAsync(CancellationToken.None);
        Assert.AreEqual(HttpStatusCode.OK, response.StatusCode);
    }
}

Para que tudo funcione, você precisará instalar um monte de pacotes Microsoft.OWIN.*e Microsoft.AspNet.*colarei packages.configaqui:

<?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="Castle.Core" version="4.3.1" targetFramework="net472" />
  <package id="EntityFramework" version="6.2.0" targetFramework="net472" />
  <package id="Microsoft.AspNet.Identity.Core" version="2.2.2" targetFramework="net472" />
  <package id="Microsoft.AspNet.Identity.EntityFramework" version="2.2.2" targetFramework="net472" />
  <package id="Microsoft.AspNet.Identity.Owin" version="2.2.2" targetFramework="net472" />
  <package id="Microsoft.AspNet.WebApi.Client" version="5.2.7" targetFramework="net472" />
  <package id="Microsoft.AspNet.WebApi.Core" version="5.2.7" targetFramework="net472" />
  <package id="Microsoft.AspNet.WebApi.Owin" version="5.2.7" targetFramework="net472" />
  <package id="Microsoft.Owin" version="4.0.1" targetFramework="net472" />
  <package id="Microsoft.Owin.Host.SystemWeb" version="4.0.1" targetFramework="net472" />
  <package id="Microsoft.Owin.Security" version="4.0.1" targetFramework="net472" />
  <package id="Microsoft.Owin.Security.Cookies" version="4.0.1" targetFramework="net472" />
  <package id="Microsoft.Owin.Security.OAuth" version="4.0.1" targetFramework="net472" />
  <package id="Moq" version="4.10.1" targetFramework="net472" />
  <package id="Newtonsoft.Json" version="12.0.1" targetFramework="net472" />
  <package id="NUnit" version="3.11.0" targetFramework="net472" />
  <package id="Owin" version="1.0" targetFramework="net472" />
  <package id="System.Runtime.CompilerServices.Unsafe" version="4.5.2" targetFramework="net472" />
  <package id="System.Threading.Tasks.Extensions" version="4.5.2" targetFramework="net472" />
</packages>

O teste é muito simples, mas demonstra que tudo funciona :-)

Teste feliz!