Defensive programming

- [Instructor] Defensive programming … is a way of programming, where the application … should behave in a consistent and predictable manner, … even in the case of unexpected conditions. … It's a way of programming where you test … for every possible edge case, … not just the most common cases … or the cases you'd most expect. … In defensive programming, we want to make sure … our functions have clear requirements, … as well as clear input and output types. … In the function implementation, … we will also want to make sure … our input satisfies certain criteria. … It's a way of making sure the computation will make sense. … Think of it this way, if I ask the question … do you write with an apple or an orange? … Does this question make sense at all? … No, it does not. … This is what defensive programming prevents. … Let's take a look at an example in code. … In this program we have the enum Shape … that can have the value Error, Rectangle or Square. … We also have a testShape function …