You are looking at a very old, but free version of the course. If you are interesed the most recent version, check it out on the Perl Maven site.
We don't want to see all the output bc generates and then try to look for the correct responses or the error messages. We'd prefer just see ok or not ok
Example 7-4. examples/bc/bc4.pl
#!/usr/bin/perl use strict; use warnings; use Expect; use Test::More qw(no_plan); $Expect::Log_Stdout = 0; my $e = Expect->new; $e->raw_pty(1); $e->spawn("bc") or die "Cannot run bc\n"; $e->expect(1, "warranty") or die "no warranty\n"; $e->send("23+7\n"); ok($e->expect(1, 30));