Welcome to JUnit in Action, which covers the JUnit framework, started by Kent Beck and Erich Gamma in late 1995. Ever since then, the popularity of the framework has been growing; now JUnit is the de facto standard for unit testing Java applications.
This book is the third edition. The first edition was a best seller, written by Vincent Massol and Ted Husted in 2003 and dedicated to version 3.x of JUnit. The second edition was also a best seller, written by Petar Tahchiev, Felipe Leme, Vincent Massol, and Gary Gregory in 2010, and dedicated to version 4.x of JUnit.
In this edition, I cover version 5.x of JUnit--the newest version--and talk about lots of features included in it. At the same time, I focus on interesting details and techniques for testing your code: the architecture of the framework, test quality, mock objects, interaction with other tools, and JUnit extensions, as well as testing layers of your application, applying the test-driven development and behavior-driven development techniques, and so forth.
This part of the book explores JUnit itself. Chapter 1 gives you a quick introduction to the concepts of testing--knowledge you need to get started. I get straight to the code, showing you how to write and execute a very simple test and see its results. Chapter 2 introduces JUnit in detail. I show JUnit 5’s capabilities and walk through the code that puts them in practice. Chapter 3 looks at JUnit architectures, and chapter 4 discusses how to make the step from JUnit 4 to JUnit 5 and how to migrate projects between these versions of the framework. Chapter 5 is dedicated to tests as a whole. The chapter describes different kinds of tests and the scenarios to which they apply. I discuss different levels of testing and the best scenarios in which to execute those tests.