Testing route configuration in ASP.NET WebApi

I was recently testing my Web API routes, and here is how I did that.

1. First, I created a helper to move all Web API routing logic there:

    public static class WebApi
    {
        public static RouteInfo RouteRequest(HttpConfiguration config, HttpRequestMessage request)
        {
            // create context
            var controllerContext = new HttpControllerContext(config, Substitute.For<IHttpRouteData>(), request);

            // get route data
            var routeData = config.Routes.GetRouteData(request);
            RemoveOptionalRoutingParameters(routeData.Values);

            request.Properties[HttpPropertyKeys.HttpRouteDataKey] = routeData;
            controllerContext.RouteData = routeData;

            // get controller type
            var controllerDescriptor = new DefaultHttpControllerSelector(config).SelectController(request);
            controllerContext.ControllerDescriptor = controllerDescriptor;

            // get action name
            var actionMapping = new ApiControllerActionSelector().SelectAction(controllerContext);

            return new RouteInfo
            {
                Controller = controllerDescriptor.ControllerType,
                Action = actionMapping.ActionName
            };
        }

        private static void RemoveOptionalRoutingParameters(IDictionary<string, object> routeValues)
        {
            var optionalParams = routeValues
                .Where(x => x.Value == RouteParameter.Optional)
                .Select(x => x.Key)
                .ToList();

            foreach (var key in optionalParams)
            {
                routeValues.Remove(key);
            }
        }
    }

    public class RouteInfo
    {
        public Type Controller { get; set; }

        public string Action { get; set; }
    }

1. Assuming I have a separate class to register Web API routes (it is created by default in Visual Studio ASP.NET MVC 4 Web Application project, in the App_Start folder):

    public static class WebApiConfig
    {
        public static void Register(HttpConfiguration config)
        {
            config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{id}",
                defaults: new { id = RouteParameter.Optional }
            );
        }
    }

1. I can test my routes easily:

    [Test]
    public void GET_api_products_by_id_Should_route_to_ProductsController_Get_method()
    {
        // setups
        var request = new HttpRequestMessage(HttpMethod.Get, "http://myshop.com/api/products/1");
        var config = new HttpConfiguration();

        // act
        WebApiConfig.Register(config);
        var route = WebApi.RouteRequest(config, request);

        // asserts
        route.Controller.Should().Be<ProductsController>();
        route.Action.Should().Be("Get");
    }

    [Test]
    public void GET_api_products_Should_route_to_ProductsController_GetAll_method()
    {
        // setups
        var request = new HttpRequestMessage(HttpMethod.Get, "http://myshop.com/api/products");
        var config = new HttpConfiguration();

        // act
        WebApiConfig.Register(config);
        var route = WebApi.RouteRequest(config, request);

        // asserts
        route.Controller.Should().Be<ProductsController>();
        route.Action.Should().Be("GetAll");
    }

    ....

Some notes below:

• Yes, I'm using absolute URLs. But I don't see any issues here, because these are fake URLs, I don't need to configure anything for them to work, and they representing real requests to our web services.
• You don't need to copy you route mappings code to the tests, if they are configured in the separate class with HttpConfiguration dependency (like in the example above).
• I'm using NUnit, NSubstitute and FluentAssertions in the above example, but of course it's an easy task to do the same with any other test frameworks.

A late answer for ASP.NET Web API 2 ( I only tested for that version ). I used MvcRouteTester.Mvc5 from Nuget and it does the job for me. you can write the following.

[TestClass]
public class RouteTests
{
    private HttpConfiguration config;
    [TestInitialize]
    public void MakeRouteTable()
    {
        config = new HttpConfiguration();
        WebApiConfig.Register(config);
        config.EnsureInitialized();
    }
    [TestMethod]
    public void GetTest()
    {
        config.ShouldMap("/api/super")
            .To<superController>(HttpMethod.Get, x => x.Get());
    }
}

I had to add nuget package Microsoft Asp.Net MVC version 5.0.0 to the test project. That's not too pretty but I didn't find a better solution and it's acceptable to me. You can install the old version like this in nuget package manager console:

Get-Project Tests | install-package microsoft.aspnet.mvc -version 5.0.0

It works with System.Web.Http.RouteAttribute too.

This answer is valid for WebAPI 2.0 and above

Reading through Whyleee's answer, I noticed that the approach is based on coupled and fragile assumptions:

1. The approach tries to recreate the action selection, and assumes internal implementation details in Web API.
2. It assumes that the default controller selector is being used, when there is a well known public extensiblity point that allows replacing it.

An alternative approach is to use an light-weight functional test. The steps in this approach are are:

1. Initialize a test HttpConfiguration object using your WebApiConfig.Register method, mimicking the way the app would be initialized in a real world.
2. Add a custom authentication filter to the test configuration object that captures the action information at that level. This can be injected or done directly in the product code via a switch. 2.1 The authentication filter will short-circuit any filters as well as the action code, so there are no concerns with the actual code being run in the action method itself.
3. Use the in-memory server (HttpServer), and make a request. This approach uses an in-memory channel, so it would not hit the network.
4. Compare the captured action information with the expected information.

[TestClass]
public class ValuesControllerTest
{
    [TestMethod]
    public void ActionSelection()
    {
        var config = new HttpConfiguration();
        WebApiConfig.Register(config);

        Assert.IsTrue(ActionSelectorValidator.IsActionSelected(
            HttpMethod.Post,
            "http://localhost/api/values/",
            config,
            typeof(ValuesController),
            "Post"));
    }
 }

This helper executes the pipeline, and validates data captured by the authentication filter, other properties can be captured as well OR a customer filter can be implemented that does the validation directly per test, by passing a lambda into the filter on initialization.

 public class ActionSelectorValidator
 {
    public static bool IsActionSelected(
        HttpMethod method,
        string uri,
        HttpConfiguration config,
        Type controller,
        string actionName)
    {
        config.Filters.Add(new SelectedActionFilter());
        var server = new HttpServer(config);
        var client = new HttpClient(server);
        var request = new HttpRequestMessage(method, uri);
        var response = client.SendAsync(request).Result;
        var actionDescriptor = (HttpActionDescriptor)response.RequestMessage.Properties["selected_action"];

        return controller == actionDescriptor.ControllerDescriptor.ControllerType && actionName == actionDescriptor.ActionName;
    }
}

This filter runs and blocks all other executions of filters or action code.

public class SelectedActionFilter : IAuthenticationFilter
{
    public Task AuthenticateAsync(
         HttpAuthenticationContext context,
         CancellationToken cancellationToken)
    {
        context.ErrorResult = CreateResult(context.ActionContext);

       // short circuit the rest of the authentication filters
        return Task.FromResult(0);
    }

    public Task ChallengeAsync(HttpAuthenticationChallengeContext context, CancellationToken cancellationToken)
    {
        var actionContext = context.ActionContext;

        actionContext.Request.Properties["selected_action"] = 
            actionContext.ActionDescriptor;
        context.Result = CreateResult(actionContext); 


        return Task.FromResult(0);
    }

    private static IHttpActionResult CreateResult(
        HttpActionContext actionContext)
    {
        var response = new HttpResponseMessage()
            { RequestMessage = actionContext.Request };

        actionContext.Response = response;

        return new ByPassActionResult(response);
    }

    public bool AllowMultiple { get { return true; } }
}

A result that will short circuit the execution

internal class ByPassActionResult : IHttpActionResult
{
    public HttpResponseMessage Message { get; set; }

    public ByPassActionResult(HttpResponseMessage message)
    {
        Message = message;
    }

    public Task<HttpResponseMessage> 
       ExecuteAsync(CancellationToken cancellationToken)
    {
       return Task.FromResult<HttpResponseMessage>(Message);
    }
}

I've taken Keith Jackson's solution and modified it to:

a) work with asp.net web api 2 - attribute routing as well as old school routing

    and

b) verify not only route parameter names but also their values
 

e.g. for the following routes

    [HttpPost]
    [Route("login")]
    public HttpResponseMessage Login(string username, string password)
    {
        ...
    }


    [HttpPost]
    [Route("login/{username}/{password}")]
    public HttpResponseMessage LoginWithDetails(string username, string password)
    {
        ...
    }

  You can verify the routes match the correct http method, controller, action and parameters:

    [TestMethod]
    public void Verify_Routing_Rules()
    {
        "http://api.appname.com/account/login"
           .ShouldMapTo<AccountController>("Login", HttpMethod.Post);

        "http://api.appname.com/account/login/ben/password"
            .ShouldMapTo<AccountController>(
               "LoginWithDetails", 
               HttpMethod.Post, 
               new Dictionary<string, object> { 
                   { "username", "ben" }, { "password", "password" } 
               });
    }

  Modifications to Keith Jackson's modifications to whyleee's solution.

    public static class RoutingTestHelper
    {
        /// <summary>
        ///     Routes the request.
        /// </summary>
        /// <param name="config">The config.</param>
        /// <param name="request">The request.</param>
        /// <returns>Inbformation about the route.</returns>
        public static RouteInfo RouteRequest(HttpConfiguration config, HttpRequestMessage request)
        {
            // create context
            var controllerContext = new HttpControllerContext(config, new Mock<IHttpRouteData>().Object, request);

            // get route data
            var routeData = config.Routes.GetRouteData(request);
            RemoveOptionalRoutingParameters(routeData.Values);

            HttpActionDescriptor actionDescriptor = null;
            HttpControllerDescriptor controllerDescriptor = null;

            // Handle web api 2 attribute routes
            if (routeData.Values.ContainsKey("MS_SubRoutes"))
            {
                var subroutes = (IEnumerable<IHttpRouteData>)routeData.Values["MS_SubRoutes"];
                routeData = subroutes.First();
                actionDescriptor = ((HttpActionDescriptor[])routeData.Route.DataTokens.First(token => token.Key == "actions").Value).First();
                controllerDescriptor = actionDescriptor.ControllerDescriptor;
            }
            else
            {
                request.Properties[HttpPropertyKeys.HttpRouteDataKey] = routeData;
                controllerContext.RouteData = routeData;

                // get controller type
                controllerDescriptor = new DefaultHttpControllerSelector(config).SelectController(request);
                controllerContext.ControllerDescriptor = controllerDescriptor;

                // get action name
                actionDescriptor = new ApiControllerActionSelector().SelectAction(controllerContext);

            }

            return new RouteInfo
            {
                Controller = controllerDescriptor.ControllerType,
                Action = actionDescriptor.ActionName,
                RouteData = routeData
            };
        }


        #region | Extensions |

        public static bool ShouldMapTo<TController>(this string fullDummyUrl, string action, Dictionary<string, object> parameters = null)
        {
            return ShouldMapTo<TController>(fullDummyUrl, action, HttpMethod.Get, parameters);
        }

        public static bool ShouldMapTo<TController>(this string fullDummyUrl, string action, HttpMethod httpMethod, Dictionary<string, object> parameters = null)
        {
            var request = new HttpRequestMessage(httpMethod, fullDummyUrl);
            var config = new HttpConfiguration();
            WebApiConfig.Register(config);
            config.EnsureInitialized();

            var route = RouteRequest(config, request);

            var controllerName = typeof(TController).Name;
            if (route.Controller.Name != controllerName)
                throw new Exception(String.Format("The specified route '{0}' does not match the expected controller '{1}'", fullDummyUrl, controllerName));

            if (route.Action.ToLowerInvariant() != action.ToLowerInvariant())
                throw new Exception(String.Format("The specified route '{0}' does not match the expected action '{1}'", fullDummyUrl, action));

            if (parameters != null && parameters.Any())
            {
                foreach (var param in parameters)
                {
                    if (route.RouteData.Values.All(kvp => kvp.Key != param.Key))
                        throw new Exception(String.Format("The specified route '{0}' does not contain the expected parameter '{1}'", fullDummyUrl, param));

                    if (!route.RouteData.Values[param.Key].Equals(param.Value))
                        throw new Exception(String.Format("The specified route '{0}' with parameter '{1}' and value '{2}' does not equal does not match supplied value of '{3}'", fullDummyUrl, param.Key, route.RouteData.Values[param.Key], param.Value));
                }
            }

            return true;
        }

        #endregion


        #region | Private Methods |

        /// <summary>
        ///     Removes the optional routing parameters.
        /// </summary>
        /// <param name="routeValues">The route values.</param>
        private static void RemoveOptionalRoutingParameters(IDictionary<string, object> routeValues)
        {
            var optionalParams = routeValues
                .Where(x => x.Value == RouteParameter.Optional)
                .Select(x => x.Key)
                .ToList();

            foreach (var key in optionalParams)
            {
                routeValues.Remove(key);
            }
        }

        #endregion
    }

    /// <summary>
    ///     Route information
    /// </summary>
    public class RouteInfo
    {
        public Type Controller { get; set; }
        public string Action { get; set; }
        public IHttpRouteData RouteData { get; set; }
    }

Thanks to whyleee for the answer above!

I've combined it with some of the elements I liked syntactically from the WebApiContrib.Testing library, which wasn't working for me to generate the following helper class.

This allows me to write really lightweight tests like this...

[Test]
[Category("Auth Api Tests")]
public void TheAuthControllerAcceptsASingleItemGetRouteWithAHashString()
{
    "http://api.siansplan.com/auth/sjkfhiuehfkshjksdfh".ShouldMapTo<AuthController>("Get", "hash");
}

[Test]
[Category("Auth Api Tests")]
public void TheAuthControllerAcceptsAPost()
{
    "http://api.siansplan.com/auth".ShouldMapTo<AuthController>("Post", HttpMethod.Post);
}

I've also enhanced it slightly to allow testing for parameters when needed (this is a params array so you can add all you like and it just checks they are present). This has also been adapted for MOQ, purely as it's my framework of choice...

using Moq;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using System.Web.Http;
using System.Web.Http.Controllers;
using System.Web.Http.Dispatcher;
using System.Web.Http.Hosting;
using System.Web.Http.Routing;

namespace SiansPlan.Api.Tests.Helpers
{
    public static class RoutingTestHelper
    {
        /// <summary>
        /// Routes the request.
        /// </summary>
        /// <param name="config">The config.</param>
        /// <param name="request">The request.</param>
        /// <returns>Inbformation about the route.</returns>
        public static RouteInfo RouteRequest(HttpConfiguration config, HttpRequestMessage request)
        {
            // create context
            var controllerContext = new HttpControllerContext(config, new Mock<IHttpRouteData>().Object, request);

            // get route data
            var routeData = config.Routes.GetRouteData(request);
            RemoveOptionalRoutingParameters(routeData.Values);

            request.Properties[HttpPropertyKeys.HttpRouteDataKey] = routeData;
            controllerContext.RouteData = routeData;

            // get controller type
            var controllerDescriptor = new DefaultHttpControllerSelector(config).SelectController(request);
            controllerContext.ControllerDescriptor = controllerDescriptor;

            // get action name
            var actionMapping = new ApiControllerActionSelector().SelectAction(controllerContext);

            var info = new RouteInfo(controllerDescriptor.ControllerType, actionMapping.ActionName);

            foreach (var param in actionMapping.GetParameters())
            {
                info.Parameters.Add(param.ParameterName);
            }

            return info;
        }

        #region | Extensions |

        /// <summary>
        /// Determines that a URL maps to a specified controller.
        /// </summary>
        /// <typeparam name="TController">The type of the controller.</typeparam>
        /// <param name="fullDummyUrl">The full dummy URL.</param>
        /// <param name="action">The action.</param>
        /// <param name="parameterNames">The parameter names.</param>
        /// <returns></returns>
        public static bool ShouldMapTo<TController>(this string fullDummyUrl, string action, params string[] parameterNames)
        {
            return ShouldMapTo<TController>(fullDummyUrl, action, HttpMethod.Get, parameterNames);
        }

        /// <summary>
        /// Determines that a URL maps to a specified controller.
        /// </summary>
        /// <typeparam name="TController">The type of the controller.</typeparam>
        /// <param name="fullDummyUrl">The full dummy URL.</param>
        /// <param name="action">The action.</param>
        /// <param name="httpMethod">The HTTP method.</param>
        /// <param name="parameterNames">The parameter names.</param>
        /// <returns></returns>
        /// <exception cref="System.Exception"></exception>
        public static bool ShouldMapTo<TController>(this string fullDummyUrl, string action, HttpMethod httpMethod, params string[] parameterNames)
        {
            var request = new HttpRequestMessage(httpMethod, fullDummyUrl);
            var config = new HttpConfiguration();
            WebApiConfig.Register(config);

            var route = RouteRequest(config, request);

            var controllerName = typeof(TController).Name;
            if (route.Controller.Name != controllerName)
                throw new Exception(String.Format("The specified route '{0}' does not match the expected controller '{1}'", fullDummyUrl, controllerName));

            if (route.Action.ToLowerInvariant() != action.ToLowerInvariant())
                throw new Exception(String.Format("The specified route '{0}' does not match the expected action '{1}'", fullDummyUrl, action));

            if (parameterNames.Any())
            {
                if (route.Parameters.Count != parameterNames.Count())
                    throw new Exception(
                        String.Format(
                            "The specified route '{0}' does not have the expected number of parameters - expected '{1}' but was '{2}'",
                            fullDummyUrl, parameterNames.Count(), route.Parameters.Count));

                foreach (var param in parameterNames)
                {
                    if (!route.Parameters.Contains(param))
                        throw new Exception(
                            String.Format("The specified route '{0}' does not contain the expected parameter '{1}'",
                                          fullDummyUrl, param));
                }
            }

            return true;
        }

        #endregion

        #region | Private Methods |

        /// <summary>
        /// Removes the optional routing parameters.
        /// </summary>
        /// <param name="routeValues">The route values.</param>
        private static void RemoveOptionalRoutingParameters(IDictionary<string, object> routeValues)
        {
            var optionalParams = routeValues
                .Where(x => x.Value == RouteParameter.Optional)
                .Select(x => x.Key)
                .ToList();

            foreach (var key in optionalParams)
            {
                routeValues.Remove(key);
            }
        }

        #endregion
    }

    /// <summary>
    /// Route information
    /// </summary>
    public class RouteInfo
    {
        #region | Construction |

        /// <summary>
        /// Initializes a new instance of the <see cref="RouteInfo"/> class.
        /// </summary>
        /// <param name="controller">The controller.</param>
        /// <param name="action">The action.</param>
        public RouteInfo(Type controller, string action)
        {
            Controller = controller;
            Action = action;
            Parameters = new List<string>();
        }

        #endregion

        public Type Controller { get; private set; }
        public string Action { get; private set; }
        public List<string> Parameters { get; private set; }
    }
}