Don't blame the Compiler.
In the previous chapters we have encountered here and there hints for testing individual functions. Without meaningful tests to ensure the quality of our package, all of our work would be for naught, for on what else are we to base our confidence in the reliability of our functions? Therefore, we are now going to give our full attention to this important topic, and to this end we ask two questions that every software developer should ask:
How can we be certain that our software functions behave according to their specifications, which in our case means first of all that they are mathematically correct?
How can we ...