There are more test types out there than we could cover in this chapter. If you find the world of automated testing as fascinating as the authors do, you might want to check out other test types as well, such as the following:
- Mutation testing is about modifying the code to be tested in tiny changes (so-called mutants). If your tests can catch these mutants, they are usually well written; otherwise, they will let the mutant escape. Infection is currently the best-known tool for this test type in the PHP world (https://infection.github.io).
- Visual regression testing literally compares screenshots of the application made during tests with original screenshots to catch problems in Cascading Style Sheets (CSS). While this is not directly PHP-related, it could be interesting for you if you want to keep the styling of your web project perfect. A good candidate to check is BackstopJS (https://github.com/garris/BackstopJS).
- API testing can be considered E2E...