That could be a book in itself!
In chapter 2, we provide an overview of testing approaches and introduce some frameworks. There wasn't room to go into extensive detail, but we tried to provide enough info to figure out which ones you might want to delve further into.
For use within the remainder of the book, we develop our own simple
assert() mechanism to use for testing assertions, and a technique for performance evaluation. We didn't want to use any one particular framework throughout the book, because a book that uses a framework inevitably becomes a book
about that framework, and we wanted to focus on pure JavaScript.