cards.py

def main():
    deck = Deck()
    assert deck
    assert len(deck) == 52
    assert Card(rank='2', suit='spades') == Card(rank='2', suit='spades')
    assert deck[0] == Card(rank='2', suit='spades')
    assert deck[:2] == [Card('2', 'spades'), Card('3', 'spades')]
    assert deck[12::13] == [Card('A', 'spades'), Card('A', 'diamonds'),
                            Card('A', 'clubs'), Card('A', 'hearts')]
    assert Card('Q', 'hearts') in Deck()

    deck[0] = None; assert deck[0] is None
    deck[:2] = [None, None]; assert deck[:2] == [None, None]


if __name__ == '__main__':
    main()