JUnit and TestNG are two major Java testing frameworks. You already wrote tests with JUnit in the previous chapter, Chapter 3, Red-Green-Refactor – From Failure Through Success until Perfection, and, hopefully, got a good understanding of how it works. How about TestNG? It was born out of a desire to make JUnit better. Indeed, it contains some functionalities that JUnit doesn't have.
The following subsections summarize some of the differences between the two of them. We'll try not only to provide an explanation of the differences, but also their evaluation in the context of unit testing with TDD.