$code = <<'CODE';
print "Hello World!\n";
BEGIN {print '# hacked #';}
CODE

$code =~ s/BEGIN|CHECK|INIT|END//g; # kill blocks here
$code = "{last; $code}";            # stop test code running
eval $code;

# now have a look see at $@ to see if it contains an error
# due to the test code being invalid.

print $@ ? "Invalid\n" : "Syntax OK\n";