Writing “unit testable” code?

Question

What kind of practices do you use to make your code more unit testing friendly?

Answer 1

The easiest way is don't check in your code unless you check in tests with it.

I'm not a huge fan of writing the tests first. But one thing I believe very strongly in is that code must be checked in with tests. Not even an hour or so before, togther. I think the order in which they are written is less important as long as they come in together.