Test-Driven Development

Let me start with something that actually happened. In early 2025, I added a feature to an internal system: export to Excel. Small requirement — I didn’t even write it up, just typed “add an export button to the list page” into the chat box. The AI delivered in ten minutes. Frontend changes, new endpoint, SQL — all in one pass. I was pleased when I opened the PR, right up until review revealed: the export columns didn’t match the list page, a hundred thousand rows would hang the service outright, there was no permission check, and the tests only covered the happy path.