ASP.NET MVC unit test controller with HttpContext

I am trying to write a unit test for my one controller to verify if a view was returned properly, but this controller has a basecontroller that accesses the HttpContext.Current.Session. Everytime I create a new instance of my controller is calls开发者_高级运维 the basecontroller constructor and the test fails with a null pointer exception on the HttpContext.Current.Session. Here is the code:

public class BaseController : Controller
{       
    protected BaseController()
    {
       ViewData["UserID"] = HttpContext.Current.Session["UserID"];   
    }
}

public class IndexController : BaseController
{
    public ActionResult Index()
    {
        return View("Index.aspx");
    }
}

    [TestMethod]
    public void Retrieve_IndexTest()
    {
        // Arrange
        const string expectedViewName = "Index";

        IndexController controller = new IndexController();

        // Act
        var result = controller.Index() as ViewResult;

        // Assert
        Assert.IsNotNull(result, "Should have returned a ViewResult");
        Assert.AreEqual(expectedViewName, result.ViewName, "View name should have been {0}", expectedViewName);
    }

Any ideas on how to mock (using Moq) the Session that is accessed in the base controller so the test in the descendant controller will run?

---

Unless you use Typemock or Moles, you can't.

In ASP.NET MVC you are not supposed to be using HttpContext.Current. Change your base class to use ControllerBase.ControllerContext - it has a HttpContext property that exposes the testable HttpContextBase class.

Here's an example of how you can use Moq to set up a Mock HttpContextBase:

var httpCtxStub = new Mock<HttpContextBase>();

var controllerCtx = new ControllerContext();
controllerCtx.HttpContext = httpCtxStub.Object;

sut.ControllerContext = controllerCtx;

// Exercise and verify the sut

where sut represents the System Under Test (SUT), i.e. the Controller you wish to test.

---

If you are using Typemock, you can do this:

Isolate.WhenCalled(()=>controller.HttpContext.Current.Session["UserID"])
.WillReturn("your id");

The test code will look like:

[TestMethod]
public void Retrieve_IndexTest()
{
    // Arrange
    const string expectedViewName = "Index";

    IndexController controller = new IndexController();
    Isolate.WhenCalled(()=>controller.HttpContext.Current.Session["UserID"])
    .WillReturn("your id");
    // Act
    var result = controller.Index() as ViewResult;

    // Assert
    Assert.IsNotNull(result, "Should have returned a ViewResult");
    Assert.AreEqual(expectedViewName, result.ViewName, "View name should have been {0}", expectedViewName);
}

---

Snippet:

var request = new SimpleWorkerRequest("/dummy", @"c:\inetpub\wwwroot\dummy", "dummy.html", null, new StringWriter());
var context = new HttpContext(request);
SessionStateUtility.AddHttpSessionStateToContext(context, new TestSession());
HttpContext.Current = context;

Implementation of TestSession():

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web.SessionState;

namespace m1k4.Framework.Test
{
    public class TestSession : IHttpSessionState
    {
        private Dictionary<string, object> state = new Dictionary<string, object>();

        #region IHttpSessionState Members

        public void Abandon()
        {
            throw new NotImplementedException();
        }

        public void Add(string name, object value)
        {
            this.state.Add(name, value);
        }

        public void Clear()
        {
            throw new NotImplementedException();
        }

        public int CodePage
        {
            get
            {
                throw new NotImplementedException();
            }
            set
            {
                throw new NotImplementedException();
            }
        }

        public System.Web.HttpCookieMode CookieMode
        {
            get
            {
                throw new NotImplementedException();
            }
        }

        public void CopyTo(Array array, int index)
        {
            throw new NotImplementedException();
        }

        public int Count
        {
            get
            {
                throw new NotImplementedException();
            }
        }

        public System.Collections.IEnumerator GetEnumerator()
        {
            throw new NotImplementedException();
        }

        public bool IsCookieless
        {
            get
            {
                throw new NotImplementedException();
            }
        }

        public bool IsNewSession
        {
            get
            {
                throw new NotImplementedException();
            }
        }

        public bool IsReadOnly
        {
            get
            {
                throw new NotImplementedException();
            }
        }

        public bool IsSynchronized
        {
            get
            {
                throw new NotImplementedException();
            }
        }

        public System.Collections.Specialized.NameObjectCollectionBase.KeysCollection Keys
        {
            get
            {
                throw new NotImplementedException();
            }
        }

        public int LCID
        {
            get
            {
                throw new NotImplementedException();
            }
            set
            {
                throw new NotImplementedException();
            }
        }

        public SessionStateMode Mode
        {
            get
            {
                throw new NotImplementedException();
            }
        }

        public void Remove(string name)
        {
            this.state.Remove(name);
        }

        public void RemoveAll()
        {
            this.state = new Dictionary<string, object>();
        }

        public void RemoveAt(int index)
        {
            throw new NotImplementedException();
        }

        public string SessionID
        {
            get
            {
                return "Test Session";
            }
        }

        public System.Web.HttpStaticObjectsCollection StaticObjects
        {
            get
            {
                throw new NotImplementedException();
            }
        }

        public object SyncRoot
        {
            get
            {
                throw new NotImplementedException();
            }
        }

        public int Timeout
        {
            get
            {
                return 10;
            }
            set
            {
                throw new NotImplementedException();
            }
        }

        public object this[int index]
        {
            get
            {
                throw new NotImplementedException();
            }
            set
            {
                throw new NotImplementedException();
            }
        }

        public object this[string name]
        {
            get
            {
                return this.state[name];
            }
            set
            {
                this.state[name] = value;
            }
        }

        #endregion
    }
}

---

You should probably use an ActionFilter instead of a base class for this sort of thing

[UserIdBind]
public class IndexController : Controller
{
    public ActionResult Index()
    {
        return View("Index.aspx");
    }
}

---

I'd checkout the ASP.NET-MVC book listed here -- toward the end, there is a good section on Mocking framewors -- http://www.hanselman.com/blog/FreeASPNETMVCEBookNerdDinnercomWalkthrough.aspx