There is no way of knowing whether something is working as expected if it has not been tested. Treating the Infrastructure as Code offers us the ability to test the code used to accomplish this goal, to validate and be sure that it works as expected. Otherwise, you will need to do these validations manually, and think about the debugging process involved at this level to identify where the errors are. Even when you could have Infrastructure as Code without testing, it's highly recommended to run tests on the scripts that have been created.

Embracing the Infrastructure as Code approach will help us to take full advantage of computers and systems, in order to make the process less tedious for us, and people should only be working in front of a data center when an issue occurs. This will also help you to keep your infrastructure up to date in a quick and easy manner. If you want an in-depth understanding of how to embrace this approach effectively, I encourage you to read the Infrastructure as Code book by Kief Morris.