My point was it's a top-down process with different layers of tests and POC.
The API tests of the top layer are stable, the POCs less so.
There is no point in starting a long endeavor without
- clarifying the clients expectations
- proving the feasibility
This is best done with some demo code, and this can and should be tested. Written specifications are open for interpretations, tests let you sleep well.
Since those tests define your API they can't easily be thrown away anymore unless your POCs were bad.
Hope my perspective is clearer now.
(addicted to the 𐍀𐌴𐍂𐌻 Programming Language :)
Wikisyntax for the Monastery