I'm now having Claude Code build the tests for my voicenotes organization application. For the most basic implementation - just a single text field - I wrote in English which tests I know I need, there were about two dozen. Approaching size limits, unicode, normalization, nonprinting characters, Hebrew vowel points, empty strings vs NULL strings, Exceeded byte length without exceeded character length, etc etc. I then threw Claude Code at it.

Claude Code found more edge cases to write tests for than I ever would have thought of. And I've been doing this for 20 years.