Unit Testing Principles, Practices, and Patterns

Chapter 6. Styles of unit testing

This chapter covers

• Comparing styles of unit testing
• The relationship between functional and hexagonal architectures
• Transitioning to output-based testing

Chapter 4 introduced the four attributes of a good unit test: protection against regressions, resistance to refactoring, fast feedback, and maintainability. These attributes form a frame of reference that you can use to analyze specific tests and unit testing approaches. We analyzed one such approach in chapter 5: the use of mocks.

In this chapter, I apply the same frame of reference to the topic of unit testing styles. There are three such styles: output-based, state-based, and communication-based testing. Among the three, the output-based style produces ...