For a deep verification, you can monitor the outputs and then verify
that
for the given outputs (and transitions) the correct stimulii were
received,
i.e. no false switching as well as correct behaviour for usual inputs.
This does mean firing a whole load of different vectors at the inputs,
using
all possible combinations of multi valued logic 0, 1, Z, and maybe X.
Just an idea.
Kev P.
