I sit down with them and have them write code. I give them a problem, a test suite, and an editor of their choice. Their challenge is to get as many tests as p

I sit down with them and have them write code. I give them a problem, a test suite, and an editor of their choice. Their challenge is to get as many tests as possible to pass. It's not really intended to get all of them - they branch into different areas, and the candidate can choose the direction they would like to move in.