The tests help you discover what needs to be written, too. Honestly, I can’t imagine starting to write code unless I have at least a rough concept of what to write.

Maybe I’m being judgemental (I don’t mean to be) but what I am trying to say is that, in my experience, writing tests as you code has usually lead to the best outcomes and often the fastest delivery times.

This is why you write the test before the code. You write the test to make sure something fails, then you write the code to make it pass. Then you repeat this until all your behaviors are captured in code. It’s called TDD

But, full marks for writing tests in the first place