UTC May  months later I have also used testdriven development and noticed that even a few representative tests can be used to detect problems  it was not necessary to have complete testcoverage of all functions just a few limited tests would provide a sanity check to the usability of the unit in general  The limitedtests approach reduces the amount of testcases that must be updated if the unit changes significantly although it could be argued that more tests would provide more protectionreliability in the future and pay for themselves even when needing to be updated to match significant changes  Dr Deming advocated a return to mass inspection to handle extreme safety concerns    May