Pragmatic Unit Testing in Java with JUnit, 3rd Edition

Chapter 2Testing the Building Blocks

In the previous chapter, you took a small piece of code and wrote a few JUnit tests around it. In the process, you learned how to structure your tests, execute them, how to interpret results, and what test to write next.

You’ve only scratched the surface of what it means to write tests for code. In this chapter, you’ll examine several common code constructs and learn how to test them. These are the topics you’ll cover:

• Testing pure functions
• Testing code with side effects
• How different designs can impact unit tests
• Writing tests for code involving lists
• Writing tests for code that throws exceptions
• Covering boundary conditions with tests

First, however, let’s talk about the word unit in unit test.