Let's say you're at the airport by the self-service check-in trying to print your boarding card. The machine does not accept your booking number at first, but after a few retries, you're able to check in. After confirming, the machine hangs before printing your boarding card and you're not sure whether you've checked in or not. You move on to the next machine to try again.

In our society today, we put so much of our faith in machines. They handle everything for us, from flying airplanes to shopping online and paying the bills. It is when it doesn't work that we stop in our tracks and reflect on the fact that while the machine might be perfect, the programmer is not.

The reason behind testing is to create stability, predictability, and quality in our software. Writing tests reduces the number of bugs produced and the number of bugs found by our testers.

We write tests to make software cheaper. We do this because bugs are expensive. We do this because change is expensive. And we do this because we would rather go slowly and methodically in the right direction, than very fast down the wrong lane.

In this chapter, we touched upon what test automation is and why it's necessary. The next chapter will look at functional programming and how it makes testing a breeze.