Field notes
What I learn testing checkouts, commerce platforms, customer data and AI features, written up so you can use it. Every note has something to play with and a test kit to take away.
How to test an AI agent that never answers the same way twice
Rubrics instead of exact matches, adversarial prompts mapped to the OWASP LLM Top 10, and checking the action, not the sentence. With an agent you can break.
Read the note
Where did the cent go?
Two calculations, both correct, one cent apart. Floats, rounding rules, discount splits, tax and refunds, with five things to play with and a twelve-case test kit.
Read the noteOn the bench next
- The ZIP code that sends you to the wrong storeBoundaries, geocoding and the edge of the map, from testing a store finder for a retailer with 100+ stores.Shopify
- Your API is correct and still too slowResponse-time budgets, what to measure, and how to write the recommendation a developer will actually act on.APIs