From the OneTrueWiki:

add a test, get it to fail, and write code to pass the test

From Blade Runner:

Tyrell: Is this to be an empathy test?
(…)
Tyrell: Demonstrate it. I want to see it work.
Deckard: Where’s the subject?
Tyrell: I want to see it work on a person. I want to see a negative
before I provide you with a positive.