You start a brand new Ruby project. You elegantly glide around your application sprinkling it with tests using tools like Cucumber. Time passes, test numbers grow and suddenly you find yourself wading through the thick sludgy swamp of a 1-hour test build. Your ability to deliver code in a timely manner gets difficult. Discipline gets slack ?Well I know that fix will turn the build green, just deploy it anyway?. Commit code now, find out in an hour if it breaks.