#!/usr/bin/perl 
    
use strict;
use warnings;
    
while (<DATA>) {
    chomp;
    my $orig = $_;
    
    s/'/'"'"'/g;
    my $result = `echo '$_' | cat`;
    chomp $result;

    print STDERR "Mismatch [$orig] vs [$result]\n" unless $result eq $orig;
}

__DATA__   
foo bar  
'foo bar' 
foo'"'bar 
''''''''''''
'''''''''''
"foo'bar"  
"foo''bar"   
"foo'bar""
'
"'"