5.12. Forget about your "plan", use "no_plan"

Example 5-17. examples/intro/t12_calc.t

#!/usr/bin/perl
use strict;
use warnings;

my %tests = (
    '1 + 1'     => 2,
    '2 + 2'     => 4,
    '2 + 2 + 2' => 6,
    '1+1'       => 2,
    '0+ -1'     => -1,
    '0-1'       => -1,
    '-1+1'      => 0,
);

use Test::Simple "no_plan";

foreach my $t ( keys %tests ) {
    ok( `./mycalc $t` == $tests{$t}, $t );
}

Example 5-18. examples/intro/t12_calc.out

ok 1 - 0-1
ok 2 - 1 + 1
ok 3 - -1+1
ok 4 - 0+ -1
ok 5 - 1+1
not ok 6 - 2 + 2 + 2
#   Failed test '2 + 2 + 2'
#   in t12_calc.t at line 18.
ok 7 - 2 + 2
1..7
# Looks like you failed 1 test of 7.