#!perl -l
use warnings;

print "-f:";
-f '""'
  ? print "Returned True (unwanted behaviour)\n"
  : print "Returned False (wanted behaviour)\n";

print "defined -f:";        
defined -f '""'
  ? print "Returned True (unwanted behaviour)\n"
  : print "Returned False (wanted behaviour)\n";

print "-T || -B:";
(-T '""' || -B '""')
  ? print "Returned True (unwanted behaviour)\n"
  : print "Returned False (wanted behaviour)\n";

print "defined -T:";
defined -T '""'
  ? print "Returned True (unwanted behaviour)\n"
  : print "Returned False (wanted behaviour)\n";

print "defined -B:";
defined -B '""'
  ? print "Returned True (unwanted behaviour)\n"
  : print "Returned False (wanted behaviour)\n";