A flat list of 1000+ tests can be quite hard to manage. Fortunately, tests, like source files, often come in related groups.
It's good to be able to organize tests into suites somehow. This is useful for supporting use case:
How to do this? With phpunit+Selenium, it's easy. We just use the Suite class of phpunit.
For TikiTests, we would need to write some sort of batch script that knew about groups of tests and could execute groups that the user asks for.