In Parts 1-3, we talked about why LLMs fail and how to categorize those failures. Now comes the hard part: actually testing for them. Not with theoretical benchmarks, but with the messy, realistic scenarios that will bite you at 2 AM on a Sunday when you’re trying to enjoy your kid’s soccer game.
Look, I’ve screwed this up more times than I care to admit. I once spent two weeks building what I thought was a comprehensive test suite, only to have Claude hallucinate SQL injection vulnerabilities in our code review tool on day three of production. The test suite was garbage because it tested what I thought would fail, not what actually fails in production.