use strict; use t::TestYAML (); use JSON::Syck; use Test::More; plan tests => 2; my $str = "foo"; my $r = { foo => \$str, bar => sub { return "bar" } }; local $SIG{__WARN__} = sub { 1 }; my $dump = JSON::Syck::Dump $r; like $dump, qr/"bar":null/; unlike $dump, qr[!perl/ref];