Where do I find a good example of a "tests" variant (which is really installing the tests on the system)?

[MK-MacPorts at techno.ms]

I would like to introduce a tests variant for a port.

Can someone point me to a port which successfully installs a test variant?

I know that I can build and run tests when building ports (i.e. when I only run “sudo port build; cd build; ctest …”).

But I want that all needed test files get actually installed in the system and not only built and removed again.
So, I’d like to know where to place which files below ${destroot}.

Greets,
Marko