If you survey hardware design groups, you will learn that between
60% and 80% of their effort is dedicated to verification. This may
seem unusually large, but I include in "verification" all debugging
and correctness checking activities, not just writing and running
testbenches. Every time a hardware designer pulls up a waveform
viewer, he or she performs a verification task. With today’s ASIC
and FPGA sizes and geometries, getting a design to fit and run at
speed is no longer the main challenge. It is to get the right design,
working as intended, at the right time.
Unlike synthesizable coding, there is no particular coding style nor
language required for verification. The freedom of using any language
that can be interfaced to a simulator and of using any features
of that language has produced a wide array of techniques and
approaches to verification. The continued absence of constraints
and historical shortage of available expertise in verification, coupled
with an apparent under-appreciation of and under-investment
in the verification function, has resulted in several different ad hoc
approaches. The consequences of an informal, ill-equipped and
understaffed verification process can range from a non-functional
design requiring several re-spins, through a design with only a subset
of the intended functionality, to a delayed product shipment.