def test_datetime_combinations():
    """test for datetime_diff."""
    now = datetime.datetime.now()
    olddate = datetime.datetime(now.year - 2, now.month, now.day, now.hour,
                                now.minute, now.second - 2)
    assert (datetime_diff.datetime_diff(olddate, now) ==
            "2 years, 2 seconds ago.")
    olddate = datetime.datetime(now.year - 2, now.month, now.day, now.hour,
                                now.minute - 2, now.second)
    assert (datetime_diff.datetime_diff(olddate, now) ==
            "2 years, 2 minutes ago.")
    olddate = datetime.datetime(now.year - 2, now.month, now.day, now.hour - 2,
                                now.minute, now.second)
    assert datetime_diff.datetime_diff(olddate, now) == "2 years, 2 hours ago."
    olddate = datetime.datetime(now.year - 2, now.month, now.day - 2, now.hour,
                                now.minute, now.second)
    assert datetime_diff.datetime_diff(olddate, now) == "2 years, 2 days ago."
    olddate = datetime.datetime(now.year - 2, now.month - 2, now.day, now.hour,
                                now.minute, now.second)
    assert (datetime_diff.datetime_diff(olddate, now) ==
            "2 years, 2 months ago.")
    olddate = datetime.datetime(now.year - 2, now.month - 2, now.day - 2,
                                now.hour, now.minute, now.second)
    assert (datetime_diff.datetime_diff(olddate, now) ==
            "2 years, 2 months, 2 days ago.")
    olddate = datetime.datetime(now.year - 2, now.month - 2, now.day - 2,
                                now.hour - 2, now.minute, now.second)
    assert (datetime_diff.datetime_diff(olddate, now) ==
            "2 years, 2 months, 2 days, 2 hours ago.")
    olddate = datetime.datetime(now.year - 2, now.month - 2, now.day - 2,
                                now.hour - 2, now.minute - 2, now.second)
    assert (datetime_diff.datetime_diff(olddate, now) ==
            "2 years, 2 months, 2 days, 2 hours, 2 minutes ago.")
    olddate = datetime.datetime(now.year - 2, now.month - 2, now.day - 2,
                                now.hour - 2, now.minute - 2, now.second - 2)
    assert (datetime_diff.datetime_diff(olddate, now) ==
            "2 years, 2 months, 2 days, 2 hours, 2 minutes, 2 seconds ago.")
def test_multiple_seconds():
    """test for datetime_diff."""
    now = datetime.datetime.now()
    olddate = datetime.datetime(now.year, now.month, now.day, now.hour,
                                now.minute, now.second - 2)
    assert datetime_diff.datetime_diff(olddate, now) == "2 seconds ago."
def test_minutes():
    """test for datetime_diff."""
    now = datetime.datetime.now()
    olddate = datetime.datetime(now.year, now.month, now.day, now.hour,
                                now.minute - 1, now.second)
    assert datetime_diff.datetime_diff(olddate, now) == "1 minute ago."
def test_datetime_diff():
    """test for datetime_diff."""
    oldnow = datetime.datetime.now()
    time.sleep(15)
    newnow = datetime.datetime.now()
    assert datetime_diff.datetime_diff(oldnow, newnow) == "15 seconds ago."