Joel is letting them off easy when he talks about how it's unlikely that this bug would come out in testing. He's right that black-box tests wouldn't catch it.

Joel is letting them off easy when he talks about how it's unlikely that this bug would come out in testing. He's right that black-box tests wouldn't catch it. But, obviously someone wrote some special-case logic for formatting 65535 and 65536, and there's absolutely no reason that that special case logic should be there. That code should have been flagged during code review and terminated with extreme prejudice.