Rhino mocks : mock property to return default (null) value

Question

If I will use dynamic mock and try to use a property that is not set up, it will simply return default(null) for this property.

I need the same behaviour in Partial Mock only for one property. I need that this property return null. (property should be not virtual)

For example:

public abstract class SomeClass
{ 
    public XmlDocument SomeProperty     
    {   
     get { return _someProperty ?? (_someProperty = SomeMethod()); } 
    //this getter should return null in my case and doesn't call SomeMethod
    }
}


[Test]
public void SomeTest()
{
    //Arrange
    var obj = MockRepository.GeneratePartialMock<SomeClass>();

    //Act
    obj.Act(); // this method will use SomeProperty

    //Assert
    ...
}