def test_repository_returns_none_when_there_are_no_previous_articles(session_factory):
repo = SqlAlchemyRepository(session_factory)
article = repo.get_article(1)
previous_date = repo.get_date_of_previous_article(article)
assert previous_date is None
def test_repository_returns_date_of_previous_article(session_factory):
repo = SqlAlchemyRepository(session_factory)
article = repo.get_article(6)
previous_date = repo.get_date_of_previous_article(article)
assert previous_date.isoformat() == '2020-03-01'
