How can you unit test ASP.NET Web API routing?

The best way to test your routes for your ASP.NET Web API application is the integration test your endpoints.

Here is simple Integration test sample for your ASP.NET Web API application. This doesn't mainly test your routes but it invisibly tests them. Also, I am using XUnit, Autofac and Moq here.

[Fact, NullCurrentPrincipal]
public async Task 
    Returns_200_And_Role_With_Key() {

    // Arrange
    Guid key1 = Guid.NewGuid(),
         key2 = Guid.NewGuid(),
         key3 = Guid.NewGuid(),
         key4 = Guid.NewGuid();

    var mockMemSrv = ServicesMockHelper
        .GetInitialMembershipService();

    mockMemSrv.Setup(ms => ms.GetRole(
            It.Is<Guid>(k =>
                k == key1 || k == key2 || 
                k == key3 || k == key4
            )
        )
    ).Returns<Guid>(key => new Role { 
        Key = key, Name = "FooBar"
    });

    var config = IntegrationTestHelper
        .GetInitialIntegrationTestConfig(GetInitialServices(mockMemSrv.Object));

    using (var httpServer = new HttpServer(config))
    using (var client = httpServer.ToHttpClient()) {

        var request = HttpRequestMessageHelper
            .ConstructRequest(
                httpMethod: HttpMethod.Get,
                uri: string.Format(
                    "https://localhost/{0}/{1}", 
                    "api/roles", 
                    key2.ToString()),
                mediaType: "application/json",
                username: Constants.ValidAdminUserName,
                password: Constants.ValidAdminPassword);

        // Act
        var response = await client.SendAsync(request);
        var role = await response.Content.ReadAsAsync<RoleDto>();

        // Assert
        Assert.Equal(key2, role.Key);
        Assert.Equal("FooBar", role.Name);
    }
}

There are a few external helpers I use for this test. The one of them is the NullCurrentPrincipalAttribute. As your test will run under your Windows Identity, the Thread.CurrentPrincipal will be set with this identity. So, if you are using some sort of authorization in your application, it is best to get rid of this in the first place:

public class NullCurrentPrincipalAttribute : BeforeAfterTestAttribute {

    public override void Before(MethodInfo methodUnderTest) {

        Thread.CurrentPrincipal = null;
    }
}

Then, I create a mock MembershipService. This is application specific setup. So, this will be changed for your own implementation.

The GetInitialServices creates the Autofac container for me.

private static IContainer GetInitialServices(
    IMembershipService memSrv) {

    var builder = IntegrationTestHelper
        .GetEmptyContainerBuilder();

    builder.Register(c => memSrv)
        .As<IMembershipService>()
        .InstancePerApiRequest();

    return builder.Build();
}

The GetInitialIntegrationTestConfig method is just initializes my configuration.

internal static class IntegrationTestHelper {

    internal static HttpConfiguration GetInitialIntegrationTestConfig() {

        var config = new HttpConfiguration();
        RouteConfig.RegisterRoutes(config.Routes);
        WebAPIConfig.Configure(config);

        return config;
    }

    internal static HttpConfiguration GetInitialIntegrationTestConfig(IContainer container) {

        var config = GetInitialIntegrationTestConfig();
        AutofacWebAPI.Initialize(config, container);

        return config;
    }
}

The RouteConfig.RegisterRoutes method basically registers my routes. I also have a little extension method to create an HttpClient over the HttpServer.

internal static class HttpServerExtensions {

    internal static HttpClient ToHttpClient(
        this HttpServer httpServer) {

        return new HttpClient(httpServer);
    }
}

Finally, I have a static class called HttpRequestMessageHelper which has bunch of static methods to construct a new HttpRequestMessage instance.

internal static class HttpRequestMessageHelper {

    internal static HttpRequestMessage ConstructRequest(
        HttpMethod httpMethod, string uri) {

        return new HttpRequestMessage(httpMethod, uri);
    }

    internal static HttpRequestMessage ConstructRequest(
        HttpMethod httpMethod, string uri, string mediaType) {

        return ConstructRequest(
            httpMethod, 
            uri, 
            new MediaTypeWithQualityHeaderValue(mediaType));
    }

    internal static HttpRequestMessage ConstructRequest(
        HttpMethod httpMethod, string uri,
        IEnumerable<string> mediaTypes) {

        return ConstructRequest(
            httpMethod,
            uri,
            mediaTypes.ToMediaTypeWithQualityHeaderValues());
    }

    internal static HttpRequestMessage ConstructRequest(
        HttpMethod httpMethod, string uri, string mediaType, 
        string username, string password) {

        return ConstructRequest(
            httpMethod, uri, new[] { mediaType }, username, password);
    }

    internal static HttpRequestMessage ConstructRequest(
        HttpMethod httpMethod, string uri, 
        IEnumerable<string> mediaTypes,
        string username, string password) {

        var request = ConstructRequest(httpMethod, uri, mediaTypes);
        request.Headers.Authorization = new AuthenticationHeaderValue(
            "Basic",
            EncodeToBase64(
                string.Format("{0}:{1}", username, password)));

        return request;
    }

    // Private helpers
    private static HttpRequestMessage ConstructRequest(
        HttpMethod httpMethod, string uri,
        MediaTypeWithQualityHeaderValue mediaType) {

        return ConstructRequest(
            httpMethod, 
            uri, 
            new[] { mediaType });
    }

    private static HttpRequestMessage ConstructRequest(
        HttpMethod httpMethod, string uri,
        IEnumerable<MediaTypeWithQualityHeaderValue> mediaTypes) {

        var request = ConstructRequest(httpMethod, uri);
        request.Headers.Accept.AddTo(mediaTypes);

        return request;
    }

    private static string EncodeToBase64(string value) {

        byte[] toEncodeAsBytes = Encoding.UTF8.GetBytes(value);
        return Convert.ToBase64String(toEncodeAsBytes);
    }
}

I am using Basic Authentication in my application. So, this class has some methods which construct an HttpRequestMessege with the Authentication header.

At the end, I do my Act and Assert to verify the things I need. This may be an overkill sample but I think this will give you a great idea.

Here is a great blog post on Integration Testing with HttpServer. Also, here is another great post on Testing routes in ASP.NET Web API.

hi when you going to Test your Routes the main objective is test GetRouteData() with this test you ensure that the route system recognize correctly your request and the correct route is select.

[Theory]
[InlineData("http://localhost:5240/foo/route", "GET", false, null, null)]
[InlineData("http://localhost:5240/api/Cars/", "GET", true, "Cars", null)]
[InlineData("http://localhost:5240/api/Cars/123", "GET", true, "Cars", "123")]
public void DefaultRoute_Returns_Correct_RouteData(
     string url, string method, bool shouldfound, string controller, string id)
{
    //Arrange
    var config = new HttpConfiguration();

    WebApiConfig.Register(config);

    var actionSelector = config.Services.GetActionSelector();
    var controllerSelector = config.Services.GetHttpControllerSelector();

    var request = new HttpRequestMessage(new HttpMethod(method), url);
    config.EnsureInitialized();
    //Act
    var routeData = config.Routes.GetRouteData(request);
    //Assert
    // assert
    Assert.Equal(shouldfound, routeData != null);
    if (shouldfound)
    {
        Assert.Equal(controller, routeData.Values["controller"]);
        Assert.Equal(id == null ? (object)RouteParameter.Optional : (object)id, routeData.
        Values["id"]);
    }
}

this is important but is'not enough, even checking that the correct route is selected and the correct route data are extracted does not ensure that the correct controller and action are selected this is a handy method if you not rewrite the default IHttpActionSelector and IHttpControllerSelector services with your own.

 [Theory]
        [InlineData("http://localhost:12345/api/Cars/123", "GET", typeof(CarsController), "GetCars")]
        [InlineData("http://localhost:12345/api/Cars", "GET", typeof(CarsController), "GetCars")]
        public void Ensure_Correct_Controller_and_Action_Selected(string url,string method,
                                                    Type controllerType,string actionName) {
            //Arrange
            var config = new HttpConfiguration();
            WebApiConfig.Register(config);

            var controllerSelector = config.Services.GetHttpControllerSelector();
            var actionSelector = config.Services.GetActionSelector();

            var request = new HttpRequestMessage(new HttpMethod(method),url);

            config.EnsureInitialized();

            var routeData = config.Routes.GetRouteData(request);
            request.Properties[HttpPropertyKeys.HttpRouteDataKey] = routeData;
            request.Properties[HttpPropertyKeys.HttpConfigurationKey] = config;
            //Act
            var ctrlDescriptor = controllerSelector.SelectController(request);
            var ctrlContext = new HttpControllerContext(config, routeData, request)
            {
                ControllerDescriptor = ctrlDescriptor
            };
            var actionDescriptor = actionSelector.SelectAction(ctrlContext);
            //Assert
            Assert.NotNull(ctrlDescriptor);
            Assert.Equal(controllerType, ctrlDescriptor.ControllerType);
            Assert.Equal(actionName, actionDescriptor.ActionName);
        }
    }