I thought I would share a recommendation for a really great book that I think anyone who is new to Unit Testing should read: Starting to Unit Test: Not as Hard as You Think by Erik Deitrich. I read this book many years ago but I remember it to this day because it was an eye opener to what Unit Testing essentially is.
When I read this book I was just starting to learn Unit Testing and I was having some struggles to fully grasp the concept of it. I knew how to write tests but I didn’t really get why but the author of this book had a very straightforward “no-BS” approach to explaining what Unit Testing is at its core and what mindset you need to have when working with Unit Testing. Quoting from the book:
"Unit testing. You've heard the term. Probably a lot. You know you should probably figure out how it works, since everyone's always talking about it and a lot of companies require developers to know it. But you don't really know it and you're worried that you'll look uninformed if you cop to not knowing it. Well, relax. This book assumes you have absolutely no idea how it works and walks you through the practice from the very beginning."
There are a lot of great books on this subject, like “The art of Unit Testing” among others but it can be quite heavy to jump on if you never worked with Unit Testing before and are not quite sure what’s the point of it all. That’s why this book is a really good first, and once you’ve got the basics broken down you can deep dive on the heavier stuff.
It’s also quite short, you’ll read it on a weekend! And it's cheap!