Currently the test-udev test is marked as manual, as it requires root privileges to run successfully, which typically isn't the case in a buildd environment.

In Debian we run test-udev as part of the autopkgtest tests though, for that the test needs to be installed into the systemd-tests package.
This is currently done manually in
https://anonscm.debian.org/cgit/pkg-systemd/systemd.git/tree/debian/rules#n250

Unfortunately this no longer works under meson, as test-udev now links libsystemd-shared and requires a properly set RUNPATH. The binary in the build directory has the RUNPATH set to $ORIGIN/src/shared so no longer works when installed manually via cp.

We can either make test-udev link against libsystemd-shared statically (as was done with autotools), or maybe better, install test-udev on "ninja install" but not run it on "ninja test".