A method for synthesis of easily-testable circuits in some basis admitting single fault detection tests of constant length

It is constructively proved that any Boolean function of $n$ variables may be implemented in the basis of gates $\{ x\& y, x\oplus y, 1, {\bar x}(y\vee z)\vee x(y\sim z)\}$ by a testable combinational circuit admitting a fault detection test set whose power does not exceed 4 under arbitrary single inverse or constant (stuck-at) faults at outputs of gates.