For over 15 years, I've been a big proponent of hierarchical test. Hierarchical test is the commonly used term for creating DFT (design-for-test) features and test patterns at lower level circuit ...
Design for testability (DFT) works to make a circuit more testable to ensure that it was manufactured correctly. Alfred Crouch explains the purpose of DFT in his book, Design-For-Test for Digital ICs ...