Before deleting a Hostgroup, warn that the hostgroup is in use.
Users will go through some effort when they create a Hostgroup, and assign classes and group parameters.
Then they add many hosts to this Hostgroup.
If they delete the Hostgroup (by mistake or mis-communication), this effort may be wasted.
It would be great if Foreman did not allow deletion of Hostgroups that are in use.
This can be done by using "before_destroy Ensure_not_used_by.new(:hosts, :puppetclasses)"
But ideally, the delete link should show a summary of what Hosts (and Group Parameters) will be affected after you click delete and confirm the deletion.