In this chapter, you acquired a thorough understanding of JUnit's runner architecture. You learned how to write your own extension and saw how it interacts with the tool's runtime. Based on this knowledge, we encountered several options to structure and categorize the entirety of our tests and discussed the downside of over-extensive runner use. We concluded the topic by explaining the assets and drawbacks of the different approaches to writing parameterized tests—one of the most important use cases for runners.

In the next chapter, you'll learn about a particular type of test helper that eases fixture setup and secures our tests with an automated teardown. We'll see how JUnit Rules embed tests at runtime and learn how to develop and use our own rules.