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.
But what if the expected output is:
This is the expected output of my program that should be checked. This is the expected output of my program that should be checked.
Yes, in this case they are actually the same. What if you had 300 such line pairs ? And what if 3000 ?
It would be probably much better if our testing program already compared the expected value with the actual results and would only print OK or NOT OK depending on success or failures.
OK OK NOT OK