[Unit]
Description=Test DynamicUser with User= and SupplementaryGroups=
[Service]
ExecStart=/bin/sh -x -c 'test "$$(id -G)" = "1" && test "$$(id -g)" = "1" && test "$$(id -u)" = "1"'
Type=oneshot
User=1
DynamicUser=yes
SupplementaryGroups=1