Most test runners have two stages: finding all tests, followed by executing them (or a subset thereof).

To find all tests in the repository, it is strongly recommended to use the included wpt manifest tool: the required behaviors are more complex than what are documented (especially when it comes to precedence of the various possibilities and some undocumented legacy ways to define test types), and hence its behavior should be considered the canonical definition of how to enumerate tests and find their type in the repository.

For test execution, please read the documentation for the various test types very carefully and then check your understanding on the mailing list or IRC (webclient, join channel #testing). It’s possible edge-case behavior isn’t properly documented!