Even if we make your assumption that he's specifically referring to TDD only, just because good code that didn't go through the more rigorous definitions of TDD

Even if we make your assumption that he's specifically referring to TDD only, just because good code that didn't go through the more rigorous definitions of TDD exists doesn't mean he's seen it. And plenty of crap code ships. I'd argue Linux has significantly more than 'no' tests: http://stackoverflow.com/questions/3177338/how-is-linux-kernel-tested http://stackoverflow.com/questions/3177338/how-is-linux-kern... -- it's not TDD, and it's not centralized, but then again, neither is Linux development. And while you might convince me that pre-XP kernels went without unit testing, I'd point out we hardly call them bastions of stability and security. Try certifying a 360 or ModernUI title under the Microsoft banner and see if they'll let you get away without writing a single test. I'd wager anyone who successfully accomplishes this has spent far more effort arguing why it should be allowed than writing some tests would take. And, given the sheer girth of their security processes (patching, QA certification, tracking) and toolset (through virtualization, fuzzing, unit testing, CI build servers), it would take much more effort to convince me that they do absolutely no unit testing whatsoever on their kernel in this day and age. Far more than you could reasonably give: I suspect such convincing would require breaking several NDAs and committing several felonies.