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.