Too Long; Didn't Read
Unit testing, if done the right way, will become your best buddy. The time you invest on writing tests will come handy in the most unexpected ways, once the product moves to a maintenance level. Unit tests will stay by your side as your pet doggy and bark at the silly mistakes you make during a feature addition, a refactoring or even a bug fix. Unit tests together with a static code analyser can prevent a majority of easy to make mistakes.