Example 5-10. examples/intro/t05_calc.t

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

# tell how many tests you are going to write. This is our "plan"
use Test::Simple tests => 3;

# the ok function of Test::Simple prints "ok" or "not ok"
ok `./mycalc 1 + 1` == 2;
ok `./mycalc 2 + 2` == 4;
ok `./mycalc 2 + 2 + 2` == 6;

Example 5-11. examples/intro/t05_calc.out

1..3
ok 1
ok 2
not ok 3
#   Failed test in t05_calc.t at line 11.
# Looks like you failed 1 test of 3.