phablet@ubuntu-phablet:~$ sudo udevadm test-builtin input_id relative-device-path-below-sys
[sudo] password for phablet: 
calling: test-builtin
=== trie on-disk ===
tool version:          219
file size:         6711498 bytes
header size             80 bytes
strings            1721914 bytes
nodes              4989504 bytes
Load module index
Network interface NamePolicy= disabled on kernel command line, ignoring.
timestamp of '/etc/systemd/network' changed
timestamp of '/lib/systemd/network' changed
Parsed configuration file /lib/systemd/network/99-default.link
Created link configuration context.
unable to open device '/sysrelative-device-path-below-sys'

Unload module index
Unloaded link configuration context.