doctest will automatically test to see if the deck of cards has 52 cards and is printing correctly.
to use:
To make a deck
in terminal:
$~ python3
>>> from deckofcards import *
>>> deck = Deck()
>>> deck
A deck of 52 cards.
>>> deck.print_deck()
...
(.print_deck() returns the entire list of cards.)
Shuffle your deck
>>> deck.shuffle()
Pop a card off the deck (without removing it)
>>> deck.pop_card()
5 of hearts