How do you standardize a test of ability in computing? I'm not talking of computer science, but of plain programmers - how do you test their capability in some type of standardized test? It's very difficult.

Medicine is different because it's about a lot of knowledge and being able to product that knowledge when required (same with lawyering). Programming is different in that you look up the information, the body of relevant info often changes, paradigms change constantly. You can't standardize this field (yet).