Connect the device to the desktop and verify that vcards are created in QStandardPaths::GenericDataLocation / kpeoplevcard". On my system this is ~/.local/share/kpeoplevcard
Create a dummy contact on the device and verify it is synchronized (Currently not automatic, have to disconnect and reconnect or use dbus)
Modify the dummy contact and verify the modifications are synchronized (Currently not automatic, have to disconnect and reconnect or use dbus)
Delete the dummy contact and verify the deletion is synchronized (Currently not automatic, have to disconnect and reconnect or use dbus)