Shipping an AI feature without tests means every prompt change is a gamble. A small evaluation set turns opinions into evidence.
Build a small evaluation set
Collect twenty to fifty real inputs, including awkward ones.
Write down what a good answer must contain.
Re-run the set after every prompt or model change.
Score what matters
Decide in advance which behaviors count as a pass, such as citing a source, refusing to invent facts or returning valid JSON, and track the pass rate over time.