Mock static property with moq

Question

I am pretty new to use moq. I am into creating some unit test case to HttpModule and everything works fine until I hit a static property as follows

this.applicationPath = (HttpRuntime.AppDomainAppVirtualPath.Length > 1) ? HttpRuntime.AppDomainAppVirtualPath : String.Empty;

I do not know how create mocks for static class and property like HttpRuntime.AppDomainAppVirtualPath. The context, request and response have been mocked well with sample code I get from moq. I will appreciate if somebody can help me on this.

Thanks in advance.

Answer 1

Moq can't fake static members.

As a solution you can create a wrapper class holding the static property and fake its members.
For example:

public class HttpRuntimeWrapper
{
     public virtual string AppDomainAppVirtualPath 
     { 
            get
            { 
                   return HttpRuntime.AppDomainAppVirtualPath; 
            }
     }
}

In the production code you can access this class instead of HttpRuntime and fake this property:

[Test]
public void AppDomainAppVirtualPathTest()
{
    var mock = new Moq.Mock<HttpRuntimeWrapper>();
    mock.Setup(fake => fake.AppDomainAppVirtualPath).Returns("FakedPath");

    Assert.AreEqual("FakedPath", mock.Object.AppDomainAppVirtualPath);
}

Another solution is to use Isolation framework (as Typemock Isolator) in which you can fake static classes and members.
For example:

Isolate.WhenCalled(() => HttpRuntime.AppDomainAppVirtualPath)
       .WillReturn("FakedPath");

Disclaimer - I work at Typemock

Answer 2

You cannot Moq static methods with Moq.

This is not a bad thing in reality, static methods and classes do have their place but for logic they make unit testing difficult. Naturally you'll run into them when using other libraries. To get around this you'll need to write an adapter (wrapper) around the static code, and provide an interface. For example:

class StaticClass
{
   public static int ReturnOne() 
   {
       return 1;
   }
}


interface IStatic
{
    int ReturnOne();
}

_{Note, I've ommited the concrete class that uses IStatic for the production code. All it would be is a class which uses IStatic and your production code would make use of this class, rather than StaticClass above.}

Then with Moq:

var staticMock = new Mock<IStatic>();
staticMock.Setup(s => s.ReturnOne()).Returns(2);

Answer 3

As mentioned in previous answers, you can't use MoQ on static methods, and if you need to, your best shot is to create a wrapper around the static class.

However, something I've discovered recently is the Moles project. From the homepage; "Moles allows to replace any .NET method with a delegate. Moles supports static or non-virtual methods." It might be useful for your current situation.