OWIN Self-Hosted Test Server for Integration Testing of OData and Web API

A co-worker of mine and I were recently given a task to perform integration testing on OData and Web API services. You can view his posts on the subject in his series: Part 1, Part 2, and Part 3. Traditionally, one might mock the web requests and responses, but by using the TestServer found in Microsoft.Owin.Testing namespace, we can start an in-memory HTTP server for doing full integration tests. You can get the NuGet package here.

To start create a new Unit Testing project with MS Test and a new ASP.NET MVC / Web API project. In the ASP.NET MVC / Web API project install Web API 2.2 and Web API 2.2 for OData v4.0 and OData v1-3. For the unit test project, install Web API 2.2, Web API 2.2 for OData v4.0 and OData v1-3, Web API 2.2 OWIN Self Host, Web API 2.2 OWIN, and Microsoft.Owin.Testing. Below is a sample of a unit/integration test for setting up an OWIN test server for in-memory integration testing:

namespace SelfHosting.Test
{
    using Microsoft.Owin.Testing;
    using Microsoft.VisualStudio.TestTools.UnitTesting;
    using Owin;
    using SelfHosting.Test.Models;
    using System;
    using System.Linq;
    using System.Net.Http;
    using System.Threading.Tasks;
    using System.Web.Http;
    using System.Web.Http.Dispatcher;
    using System.Web.OData.Builder;
    using System.Web.OData.Extensions;
    using WebApp.Models;

    [TestClass]
    public class SelfHostingTest
    {
        protected TestServer server;

        [TestInitialize]
        public void Setup()
        {
            server = TestServer.Create(app =>
            {
                HttpConfiguration config = new HttpConfiguration();
                WebAppFacade.WebApiConfig.Register(config);
                app.UseWebApi(config);
            });
        }

        [TestCleanup]
        public void TearDown()
        {
            if (server != null)
                server.Dispose();
        }

        [TestMethod]
        public async Task TestODataMetaData()
        {
            HttpResponseMessage response = await server.CreateRequest("/odata/?$metadata").GetAsync();

            var result = await response.Content.ReadAsAsync<ODataMetaData>();

            Assert.IsTrue(result.value.Count > 0, "Unable to obtain meta data");
        }

        [TestMethod]
        public async Task TestWebApi()
        {
            HttpResponseMessage response = await server.CreateRequest("/api/values").GetAsync();

            var result = await response.Content.ReadAsStringAsync();

            Assert.AreEqual("\"Hello from foreign assembly!\"", result, "/api/values not configured correctly");
        }

        [TestMethod]
        public async Task TestODataPeople()
        {
            HttpResponseMessage response = await server.CreateRequest("/odata/People").GetAsync();

            var result = await response.Content.ReadAsAsync<ODataResponse<Person>>();

            Assert.AreEqual(result.value.Count, 3, "Expected 3 people to return from /odata/People");
        }
    }

}

The OData meta data is serialized into a POCO (Plain old C# object):

namespace SelfHosting.Test.Models
{
    using System.Collections.Generic;

    public class ODataMetaData
    {
        public string odatacontext { get; set; }
        public List<Value> value { get; set; }
    }

    public class Value
    {
        public string name { get; set; }
        public string kind { get; set; }
        public string url { get; set; }
    }
}

By using a generic ODataResponse class, we can deserialize our OData response into any POCO:

namespace SelfHosting.Test.Models
{
    using System.Collections.Generic;

    public class ODataResponse<T>
        where T : class, new()
    {
        public string odatacontext { get; set; }
        public List<T> value { get; set; }

        public ODataResponse()
        {

        }
    }
}

The beauty about using the TestServer is that it is self-contained and the HTTP server is inaccessible outside of the process. Once the tests complete, the server is shutdown. The WebApiConfig registered with the TestServer determines which controllers and routes to load for testing. No production code needs to be changed in order to test existing Web API and OData controllers. The only problem that I have found is that attribute routes don't seem to register correctly. Perhaps I have not found the correct method of registering the attribute routes for the TestServer.

Here is the Visual Studio 2013 solution with both a web project and a unit testing project:

SelfHostingUnitTest.zip (1.39 mb)

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