title: Does anyone have metrics on the utility of formal Unit Testing?
body: <p>Does anyone have metrics on the utility of formal Unit Testing?  I see a lot of attention being paid to unit testing tools and I was curious why?</p>
  
  <p>I stopped formal unit testing over 5 or 6 years ago and the net gain in productivity seems quite high.  I stopped unit testing because I noticed that it never caught anything - let alone anything useful.  The type of errors that unit testing detects seem to be preventable by not drinking more than 2 glasses of wine/beer per hour (or 2 joints per hour).  Also - unit testing seems to create risk by allowing the developer to think that there is some safeguard to catch their mistakes.</p>
  
  <p>I do test to ensure that the code works as it should, but I do not use any tools.  I test based on the changes being made.  My production error rate for new code is approximately zero.  My error rate for changes to code is about 2-3 bugs per quarter.  The above measures are based on 4 production applications that I develop/support.</p>