[brene]

Test candidates using a real-time code editor over Skype. Give instructions, interview candidates and provide feedback via the in-browser Skype call. The in-browser code editor allows candidates to run their code and check their results. Help candidates avoid syntactic mistakes with real-time syntax highlighting for 7 popular programming languages.

[colejohnson66]

I've seen a few companies use HackerRank for this. They provide a few problems, one or two test cases, and then run your code against other provided test cases that you don't see.