facterstrict_hostname_checking setting to true disables fuzzy matching on FQDNs by progressively stripping the last part of the FQDN off until it gets a positive match.Trusted facts are baked in to the client certificate at the time that it is created, therefore these facts can only be changed if you re-issue the certificate. You can add custom trusted facts to the certificate when you create it though.
strict_variables for a Puppet equivalent of Bash's set -u unbound variable checking, or Perl's use strict pragma.