Summary

In this chapter, we talked a bit about automated testing in Drupal 9. We started with an introduction about why it's useful and actually important to write automated tests, and then briefly covered a few of the more popular types of software development testing methodologies.

Drupal has the capability for quite a lot of methodologies, as we've seen. We have unit tests—the lowest level form of testing that focuses on single architectural units and which are by far the fastest running tests of them all. Then we have Kernel tests, which are integration tests focusing on lower-level components and their interactions. Next, we have Functional tests, which are higher-level tests that focus on interactions with the browser. And finally, we have the FunctionalJavascript tests, which extend the latter and bring Selenium and Chrome into the picture to allow the testing of functionalities that depend on JavaScript.

We've also seen that all these different types...