In my opinion that is the easy part, It is a testable skill (not trick questions). I always have a dummy environment set up with a skeleton app set up and once

In my opinion that is the easy part, It is a testable skill (not trick questions). I always have a dummy environment set up with a skeleton app set up and once I am down to the last few quys I ask them to write something from scratch. Generally something simple like a CRUD screen that takes no more than an hour. I generally pair with them and work as a sound board to work out the problem with them. It is very natural and puts a real developer in an environment they are comfortable with. As soon as they see an IDE and no trick questions, the good ones tend to fall into a groove. The cool part is that I have learned so many tricks from many of these sessions.