This is a complex example as this Type is both abstract and that recursivley defines the generic parameter as itself.
Here is a small workaround:
Create a dummy abstract class that extends your type. (I will name it the same just to confuse our readers)
public abstract class ContentRating : ContentRating<ContentRating>
{}
Now you can do the following:
MockObject mock = MockManager.MockObject(typeof(ContentRating<ContentRating>));
// get the actual object
ContentRating<ContentRating> mockedObject = (ContentRating<ContentRating>)mock.Object;
