[hitchstory]

>As for what is gained, try this spelling: test driven development adds load to your interfaces at a time when you know the least about the problem you are trying to solve

If Im writing a single line of production code I should know as much as possible what requirements problem Im actually trying to solve with it first, no?

This is actually dovetails into a benefit to writing the test first. If you flesh out a user story scenario in the form of an executable test it can provoke new questions ("hm, actually I'd need the user ID on this new endpoint to satisfy this requirement...") and you can more quickly return to stakeholders ("can you send me a user ID in this API call?") and "fix" your "requirements bugs" before making more expensive lower level changes to the code.

This outside-in "flipping between one layer and the layer directly beneath it" is very effective at properly refining requirements, tests and architecture.

>And thus, the technique gets criticism from both ends -- that design work that should have been done up front is deferred

I dont think "design work" should be done up front if you can help it. I've always felt that the very best architecture emerges as a result of aggressive refactoring done within the confines of a complete set of tests that made as few architectural assumptions as possible. Why? Coz we're all bad at predicting the future and it's better if we dont try.

This is a mostly separate issue from TDD though.