They are complementary. I've had code reviews pick up gaps in unit tests (e.g. the code is covered, but the state space isn't), and I've had code reviews miss s

They are complementary. I've had code reviews pick up gaps in unit tests (e.g. the code is covered, but the state space isn't), and I've had code reviews miss some absolute doozies. Also code review is as much about sharing knowledge and reducing bus factor (if not more so) than acting like some great filter.