Based on finite-state automata (FSA) and equivalent regular expressions, the paper introduces a holistic view of fault modeling that can be carried out as a complementary step to system modeling, revealing much rationalization potential. Appropriate formal notions will be sed to introduce efficient algorithms to systematically generate and select test cases. The completeness of the test can be determined exploiting the link coverage of the state transition diagram of the FSA that models both the desired and undesired behavior of the system under test; this enables a precise scalability of the test and analysis process, leading to a better cost-effectiveness. The elements of the approach will be narrated by realistic examples which will be used also to validate the approach.