This is a book with two beginnings and one ending. The ending should be obvious: to increase your knowledge and understanding of Core Data.
Of the two beginnings, you get to choose. If you’re relatively new to either iOS development or Swift, then please read this chapter; it was written for you.
If, on the other hand, you’re intimately familiar with iOS—perhaps you even prefer to build your test cases in your own way—then I suggest you jump to Chapter 2, Under the Hood. The chapter you’re currently reading focuses on building a test application.