Computer programming (C++):

As the programs grows in size and complexity, it becomes far easier to introduce bugs into the programs. These can go unnoticed if not tested for and identified properly. For example, an if statement gives you two conditions you must test for, when the condition is true and when it is false.

Is it important to test your work/program? What are the risks of not testing or improper testing? What are your techniques or process for doing this?