Disclaimer: I'm mainly a tester that knows how to code and create applications (actually in Java, Javascript, Android, Angular, Ionic). So all these books require coding skills (though at any level) and they contain actual tester's transformation (T-Shaped, Tester 3.0, etc.)

Developer Testing: Building Quality Into Software

By Alexander Tarnowski

One of my favorite books when I put on the developer hat. Alexander explains testing very well, for both testers and developers. There're some chapters with good explanations about testing without code, and there are some chapters with a lot of code that explains testability and how to apply some testing ideas in code.

If you are a developer you’ll understand a lot of concepts and practices in the book, but nevertheless, it should help to expand your knowledge of creating quality software.

You’ll gain some knowledge about development and see that there many things that are not as easy as you'd thin. This book will show you another dimension to development. 

Reviews on Goodreads.

Find on Amazon.

The Way of the Web Tester: Reduce Bugs, Increase Quality, Have Fun

By Jonathan Rasmusson

Are you a newbie or experienced web tester? Doesn't matter. You must read this book.

Jonathan guides his explanation on the automation pyramid in an upside down way, and I believe his book is all the better for it. For testers, it is a faster read because they are used to working in the UI layer. But the author also explains really well the other layers in detail and with practical examples.

For developers in an Agile team is a must read too, because he demonstrates unit layering and mocking with some practical programming exercises.

My tip: read slowly and try to do all the exercises.

Reviews on Goodreads.

Find on Amazon.

Automating and Testing a REST API

By Alan Richardson

Alan has a super high knowledge in Selenium WebDriver (with a great course on Alan's site CompendiumDev) and author of Java for Testers.

In my opinion, you must have previous knowledge in test REST APIs (even though the author explains it).

I’ve learned some new, interesting things, like hacking the HTTP request to create data (Fuzzer). All API examples are using an XML approach. There could have been some examples using JSON but that's a minor critique - we have a lot of examples using JSON on the internet.

I also liked the chapter about API abstractions. It's a really good thing to think that your tool can be replaced to another, and the abstractions make the tests more readable.

Reviews on Goodreads.

Find on Leanpub.