test-op and dependencies

How test-op is expected to deal with tests in dependency libraries?

If my application depends on several libraries, which in turn depend on others, when a user of my application asdf system runs test-op, is it expected to only run tests of the application itself? Of my test-op implementation should explicitly load and call tests of all dependencies?

I think it's better to recommend test-op implementations to run only tests of this system itself and ASDF could provide a "recursive test op", which runs tests on the whole dependency tree.