[ntrepid8]

I'm not so sure they are separate skills. It's possible to write functions that are easy to test and functions that are hard to test.

I find that the two tasks of writing functions and tests for those functions are closely intertwined. I like for developers to write their own unit tests, and then for Q/A to develop the functional/integration tests from the perspective of the client (machine or human).

It's very difficult to come in after the fact and write unit tests for someone else's code, especially if they weren't thinking about writing testable code.