I have a method Apply() that I’d like to write a unit test for:

public override MyList Apply(MyProduct product, MyState state) 
{
    if (product.Name == "Special Name") 
    {
        state.MyProperty = 0;
        return null;
    } 
    else
    {
        return base.Apply(product, context, state);
    }
}

MyProduct inherits from another class, which inherits from BaseProduct, which contains the Name property:

public class BaseProduct 
{
    public string Name { get; set; }
}

I thought I could create a mock that returns “Special Name” for the Name property to test this method, but I kept getting an exception stating that the getter is non-overrideable and cannot be used in setup/verification – I set it up like so:

var mock = new Mock<MyProduct>();
mock.SetupProperty(product => product.Name);
mock.SetupGet(product => product.Name).Returns("Special Name");

I’m having trouble mocking properties on MyProduct in a way that allows me to pass an object to Apply() that matches the method signature.

As an attempted solution, I created an interface for my test:

public class IBaseProduct {
    string Name { get; set; }
}

In my test, I set the mock up like so:

var mock = new Mock<MyProduct>().As<IBaseProduct>();
mock.SetupProperty(product => product.Name);
mock.SetupGet(product => product.Name).Returns("Special Name");

I’m able to verify that mock.Object.Name returns “Special Name,” but when I try to pass mock.Object to Apply(), I see that the class of the object is IBaseProduct rather than MyProduct.

Is this because MyProduct (or BaseProduct) is not declared to implement IBaseProduct? I’d like to be able to write this test without changing MyProduct or BaseProduct.

I tried casting mock.Object to MyProduct like so:

Apply((MyProduct)mock.Object, state)

But when I do so, mock.Object.Name then returns null instead of “Special Name.”

How can I set this test up to mock MyProduct and return the correct Name without changing MyProduct or BaseProduct to implement IBaseProduct?