(UTC)
23May06 (+7 months later): I have also used "test-driven development" and noticed that even a few representative tests can be used to detect problems:  it was not necessary to have complete test-coverage of all functions, just a few, limited tests would provide a "sanity check" to the usability of the unit, in general.  The limited-tests approach reduces the amount of test-cases that must be updated if the unit changes significantly, although it could be argued that more tests would provide more protection/reliability 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. - 13:38, 23 May 2006