6.20. Multiply

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

use Test::More tests => 1;

is `./mycalc 2 * 2`, 4, '2*2';

Results

$ perl t10_calc.t 
1..1
Bareword found where operator expected at (eval 1) line 1, near "2 IE"
        (Missing operator before IE?)
not ok 1 - 2*2
#     Failed test (t10_calc.t at line 5)
#          got: ''
#     expected: '4'
# Looks like you failed 1 tests of 1.