There was a time when I was hiring vendors for my team (at a big company) rather than FTEs and I had a bit of leeway to diverge from the company's interviewing guidance. What I would do was sit them in front of a computer with Visual Studio and internet access for an hour and ask them to do something like write a program that restarts a service given its name, and they could use whatever (e.g. google, Wikipedia, and/or stack overflow) short of copying and pasting the code to do it. I figured if they couldn't do that, then they couldn't do it in real life either, and if they could it was good enough.