ASP.NET MVC unit test controller with HttpContext - asp.net-mvc

Question

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 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?

Answer 1

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.

Answer 2

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);
}

Answer 3

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
}
}

Answer 4

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");
}
}

Answer 5

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