#!/usr/bin/perl

my @strings = ('testing','','testing','testing');

foreach my $string (@strings) {
    my $q = $string;
    my $test = 'testing';
    warn "$test =~ /$q/?";
    warn $test =~ /\Q$q\E/;
}

__END__
testing =~ /testing/? at tmp.pl line 8.
1 at tmp.pl line 9.
testing =~ //? at tmp.pl line 8.
1 at tmp.pl line 9.
testing =~ /testing/? at tmp.pl line 8.
1 at tmp.pl line 9.
testing =~ /testing/? at tmp.pl line 8.
1 at tmp.pl line 9.