The paper presents a general test calculation principle which serves for producing tests for a wide range of possible faults: stuck-at-constant logic level (single, multiple), bridging (single), as well as behavioral (functional, single) faults. The proposed method handles multi-valued logic, where the number of logic values is unlimited. The level of circuit modeling is also allowed to vary in a wide range: switch level, gate level, functional level, etc. are equally allowed. Both combinational and sequential circuits are considered. The principle is comparatively simple, and it yields an opportunity to be realized by an efficient computer program.