When you check in something that breaks the build, the tests can drop an image of battered, bloody Doomguy directly into your terminal instead of having to go through something like <a href="http:&#x2F;&#x2F;squarism.com&#x2F;2010&#x2F;05&#x2F;23&#x2F;watchr-unit-tests-growl-doomguy&#x2F;" rel="nofollow">http:&#x2F;&#x2F;squarism.com&#x2F;2010&#x2F;05&#x2F;23&#x2F;watchr-unit-tests-growl-doomg...</a>.