How can I fake HttpContext for unit tests?

Question

I need to fake HttpContext.Current.Application table in order to access it from my unit tests.

I need to store my data somewhere. I thought that I can just pass instance of NameValueCollectionBase but as I discovered this base type has no indexer so it seems too complicated to use.

So what about faking this part of HttpContext ? Is it possible? How can I make it? Will be NUnit.Mocks helpful?

Thank you in advance...

Answer 1

Please go through below links it will help you.

http://www.java2s.com/Open-Source/CSharp/Web-Frameworks/MvcContrib/MvcContrib/TestHelper/Fakes/FakeHttpContext.cs.htm

Mocking and HttpContextBase.get_User()

Thanks Venkat

Answer 2

If you need indexes for namevaluecollection base please use below code

public static IEnumerable<KeyValuePair<string, string>> ToPairs(this NameValueCollection collection)
{
    if(collection == null)
    {
        throw new ArgumentNullException("collection");
    }

    return collection.Cast<string>().Select(key => new KeyValuePair<string, string>(key, collection[key]));
}

For just to store data and passing around test methods please use above code.

Answer 3

In this scenario I generate some stubs derived from the base classes in System.Web.Abstractions. I often use this technique for MVC applications as MVC / WebApi controllers contain an abstraction to HttpContext (HttpContextBase)

This way I can stub out HttpContext requirements in my unit / integration tests, here's a sample...

public class MockHttpApplicationState : HttpApplicationStateBase
{
    private IDictionary<string, object> _appState = new Dictionary<string, object>();

    public override void Add(string name, object value)
    {
        _appState.Add(name, value);
    }

    public override object Get(string name)
    {
        return _appState[name];
    }

    public override object this[string name]
    {
        get
        {
            return _appState[name];
        }

        set
        {
            _appState[name] = value;
        }
    }
}

public class MockHttpContext : HttpContextBase
{
    private IDictionary<string, object> _appKeys;

    public MockHttpContext()
    {

    }

    /// <summary>
    /// Accepts a dictionary of app keys to supply to the HttpApplicationState instance
    /// </summary>
    /// <param name="applicationState"></param>
    public MockHttpContext(IDictionary<string,object> applicationState)
    {
        _appKeys = applicationState;
    }

    public override Cache Cache
    {
        get
        {                
            return HttpRuntime.Cache;
        }
    }

    public override HttpApplicationStateBase Application
    {
        get
        {
            var mockAppState = new MockHttpApplicationState();

            foreach (string key in _appKeys.Keys)
            {
                mockAppState.Add(key, _appKeys[key]);
            }

            return mockAppState;
        }
    }

    public override HttpRequestBase Request
    {
        get
        {
            return new HttpRequestWrapper(new HttpRequest(null,"http://localhost",null));
        }
    }
}

Then my test can establish Controller and Http Context:

private readonly OnlineShop.MVC.Controllers.HomeController _controller = 
        new MVC.Controllers.HomeController(null,new UnitOfWork());

    [OneTimeSetUp]
    public void Init()
    {
        var appKeys = new Dictionary<string, object>();

        appKeys.Add("localhost", 1);

        var httpContext = new MockHttpContext(appKeys);

        _controller.ControllerContext = new ControllerContext()
        {
            Controller = _controller,
            RequestContext = new RequestContext(httpContext, new RouteData())    
        };                        
    }

    [Test]
    public void Index_Returns_HomeView()
    {            
        var view = _controller.Index() as ViewResult;
        var viewModel = view.Model as MVC.ViewModels.Home;

        Assert.IsInstanceOf<OnlineShop.MVC.ViewModels.Home>(viewModel);
        Assert.IsTrue(viewModel.FeaturedProducts.Count > 0);
    }

And my controller is aware of it's ambient HttpContextBase instance supplying Cache and Application state:

  public ActionResult Index()
    {                        
        string cacheKey = string.Format("FeaturedProducts-{0}",WebsiteId);
        IList<Product> productList = this.HttpContext.Cache[cacheKey] as IList<Product>;


        //My app keeps a list of website contexts in the Application. This test returns 1 based on the unit / int tests or a real world db value when hosted on IIS etc..
        int websiteId = (int)HttpContext.Application[this.Request.Url.Host];