This is precisely right: I ask people questions like the difference between an interface and an abstract class as a gauge, because I've had so many people answer them really badly.
The question wouldn't normally come out of the blue, though, but as a follow-up from part of a design exercise where they would have just used one or the other in their design, and as part of finding out whether they could justify their choice.
The question wouldn't normally come out of the blue, though, but as a follow-up from part of a design exercise where they would have just used one or the other in their design, and as part of finding out whether they could justify their choice.