These are automated functional tests. It would be interesting to know if the author uses unit test too and how he writes tests in general. Also some code:test ratio metrics would be indicative of how much weight does all this testing add.
For test strategy in general, you need a whole seminar. There's a good blog on testing over at http://googletesting.blogspot.com/ <- go there!
As for code:test ratio, I'm not sure what metric you want, but using just php files, there are ~1k active test files and ~7k php files total. So if you take into account that 1k of that 7k is the test, and some is test-setup and obsolete files we no longer use, it's maybe about 5:1 code:test. However, a lot of the code is third party OS software packages. In-house code is about 1.5:1 test:code, in my experience. These, by the way, are very rough estimates.