We once believed atoms were indivisible — until we learned they weren’t. Unit testing has followed a similar path. For years, we’ve treated “unit” as something small and sacred — a single class, a method, a function. But in real systems, that tidy definition often doesn’t hold up.

This talk is about what happens when the textbook rules meet messy, real-world code. We’ll rethink what a “unit” really is, explore better ways to test meaningful behavior, and question some long-standing assumptions. Along the way, we’ll take a peek at how AI might help us write better tests — or at least ask better questions.

If you’ve ever wondered why your tests don’t quite match the way your code actually works, you’re not alone. Let’s talk about it.