def test_timezones() -> None:
t = datetime.datetime(2017, 6, 15, 10, 16, 50, tzinfo=pytz.UTC)
assert get_next_datetime('* * * * *',
t) == datetime.datetime(2017,
6,
15,
10,
17,
tzinfo=pytz.UTC)
t = pytz.timezone('Europe/Stockholm').localize(
datetime.datetime(2017, 6, 15, 10, 16, 50))
assert get_next_datetime('* * * * *',
t) == pytz.timezone('Europe/Stockholm').localize(
datetime.datetime(2017, 6, 15, 10, 17))
assert get_next_datetime('15 */2 * * *',
t) == pytz.timezone('Europe/Stockholm').localize(
datetime.datetime(2017, 6, 15, 12, 15))
def test_aliases() -> None:
t = datetime.datetime(2017, 6, 15, 10, 16, 50)
assert get_next_datetime('@yearly', t) == datetime.datetime(2018, 1, 1)
assert get_next_datetime('@annually', t) == datetime.datetime(2018, 1, 1)
assert get_next_datetime('@monthly', t) == datetime.datetime(2017, 7, 1)
assert get_next_datetime('@daily', t) == datetime.datetime(2017, 6, 16)
assert get_next_datetime('@hourly',
t) == datetime.datetime(2017, 6, 15, 11)
assert get_next_datetime('@minutely',
t) == datetime.datetime(2017, 6, 15, 10, 17)
def test_days_with_isoweekday() -> None:
t = datetime.datetime(2017, 8, 24, 18, 1, 0)
assert get_next_datetime('0 10 1-7 * *',
t) == datetime.datetime(2017, 9, 1, 10, 0)
assert get_next_datetime('0 10 * * mon',
t) == datetime.datetime(2017, 8, 28, 10, 0)
assert get_next_datetime('0 10 1-7 * mon',
t) == datetime.datetime(2017, 8, 28, 10, 0)
assert get_next_datetime('0 10 1-25 * mon',
t) == datetime.datetime(2017, 8, 25, 10, 0)
assert get_next_datetime('0 * 1-25 * mon',
t) == datetime.datetime(2017, 8, 24, 19, 0)
assert get_next_datetime('0 * 1-24 * mon',
t) == datetime.datetime(2017, 8, 24, 19, 0)
assert get_next_datetime('0 * 1-23 * mon',
t) == datetime.datetime(2017, 8, 28, 0, 0)
def next_call_at(
cls,
current_time: float,
interval: Optional[Union[str, int]] = None,
timestamp: Optional[str] = None,
timezone: Optional[str] = None,
) -> int:
if not timezone:
tz = tzlocal.get_localzone()
else:
try:
tz = pytz.timezone(timezone or "")
except Exception as e:
raise Exception("Unknown timezone: {}".format(timezone)) from e
local_tz = tzlocal.get_localzone()
if interval is None and timestamp is not None:
if isinstance(timestamp, str):
try:
datetime_object = datetime.datetime.strptime(
timestamp, "%Y-%m-%d %H:%M:%S")
interval = "{} {} {} {} * {}".format(
datetime_object.minute,
datetime_object.hour,
datetime_object.day,
datetime_object.month,
datetime_object.year,
)
second_modifier = 1
if tz.localize(datetime_object) > local_tz.localize(
datetime.datetime.fromtimestamp(current_time)):
second_modifier = -60
next_at = get_next_datetime(
interval,
local_tz.localize(
datetime.datetime.fromtimestamp(
current_time +
second_modifier)).astimezone(tz),
)
if not next_at:
return int(current_time + 60 * 60 * 24 * 365 * 100)
return int(next_at.timestamp() + datetime_object.second)
except ValueError:
pass
try:
datetime_object = datetime.datetime.strptime(
timestamp, "%Y-%m-%d %H:%M")
interval = "{} {} {} {} * {}".format(
datetime_object.minute,
datetime_object.hour,
datetime_object.day,
datetime_object.month,
datetime_object.year,
)
next_at = get_next_datetime(
interval,
local_tz.localize(
datetime.datetime.fromtimestamp(current_time +
1)).astimezone(tz))
if not next_at:
return int(current_time + 60 * 60 * 24 * 365 * 100)
return int(next_at.timestamp())
except ValueError:
pass
try:
datetime_object = datetime.datetime.strptime(
timestamp, "%H:%M:%S")
datetime_object = datetime.datetime(
datetime.datetime.fromtimestamp(current_time).year,
datetime.datetime.fromtimestamp(current_time).month,
datetime.datetime.fromtimestamp(current_time).day,
datetime_object.hour,
datetime_object.minute,
datetime_object.second,
)
interval = "{} {} * * *".format(datetime_object.minute,
datetime_object.hour)
second_modifier = 1
if tz.localize(datetime_object) > local_tz.localize(
datetime.datetime.fromtimestamp(current_time)):
second_modifier = -60
next_at = get_next_datetime(
interval,
local_tz.localize(
datetime.datetime.fromtimestamp(
current_time +
second_modifier)).astimezone(tz),
)
if not next_at:
return int(current_time + 60 * 60 * 24 * 365 * 100)
return int(next_at.timestamp() + datetime_object.second)
except ValueError:
pass
try:
datetime_object = datetime.datetime.strptime(
timestamp, "%H:%M")
interval = "{} {} * * *".format(datetime_object.minute,
datetime_object.hour)
next_at = get_next_datetime(
interval,
local_tz.localize(
datetime.datetime.fromtimestamp(current_time +
1)).astimezone(tz))
if not next_at:
return int(current_time + 60 * 60 * 24 * 365 * 100)
return int(next_at.timestamp())
except ValueError:
pass
raise Exception("Invalid timestamp")
if interval is not None:
if isinstance(interval, int):
return int(current_time + interval)
interval_aliases: Dict[Tuple[str, ...], Union[str, int]] = {
("every second", "1s", "1 s", "1second", "1 second", "second", "secondly", "once per second"):
1,
(
"every minute",
"1m",
"1 m",
"1minute",
"1 minute",
"minute",
"minutely",
"once per minute",
):
"@minutely",
("every hour", "1h", "1 h", "1hour", "1 hour", "hour", "hourly", "once per hour"):
"@hourly",
("every day", "1d", "1 d", "1day", "1 day", "day", "daily", "once per day", "nightly"):
"@daily",
("every month", "1month", "1 month", "month", "monthly", "once per month"):
"@monthly",
(
"every year",
"1y",
"1 y",
"1year",
"1 year",
"year",
"yearly",
"once per year",
"annually",
):
"@yearly",
(
"monday",
"mondays",
"mon",
"every monday",
"once per monday",
"weekly",
"once per week",
"week",
"every week",
):
"0 0 * * 1",
("tuesday", "tuesdays", "tue", "every tuesday", "once per tuesday"):
"0 0 * * 2",
("wednesday", "wednesdays", "wed", "every wednesday", "once per wednesday"):
"0 0 * * 3",
("thursday", "thursdays", "thu", "every thursday", "once per thursday"):
"0 0 * * 4",
("friday", "fridays", "fri", "every friday", "once per friday"):
"0 0 * * 5",
("saturday", "saturdays", "sat", "every saturday", "once per saturday"):
"0 0 * * 6",
("sunday", "sundays", "sun", "every sunday", "once per sunday"):
"0 0 * * 0",
("weekday", "weekdays", "every weekday"):
"0 0 * * 1-5",
("weekend", "weekends", "every weekend"):
"0 0 * * 0,6",
}
interval = interval.lower()
if interval.endswith("s") or interval.endswith("seconds"):
try:
interval = int(
interval.replace("seconds",
"").replace("s", "").replace(" ", ""))
except ValueError:
pass
try:
interval_value: Union[str, int] = [
v for k, v in interval_aliases.items() if interval in k
][0]
except IndexError:
interval_value = interval
if isinstance(interval_value, int):
return int(current_time + interval_value)
try:
next_at = get_next_datetime(
interval_value,
local_tz.localize(
datetime.datetime.fromtimestamp(current_time +
1)).astimezone(tz))
if not next_at:
return int(current_time + 60 * 60 * 24 * 365 * 100)
return int(next_at.timestamp())
except Exception:
raise Exception("Invalid interval")
return int(current_time + 60 * 60 * 24 * 365 * 100)
def test_isoweekday() -> None:
t = datetime.datetime(2017, 6, 15, 10, 16, 50)
assert get_next_datetime('* * * * 0',
t) == datetime.datetime(2017, 6, 18, 0, 0)
assert get_next_datetime('* * * * 1',
t) == datetime.datetime(2017, 6, 19, 0, 0)
assert get_next_datetime('* * * * 2',
t) == datetime.datetime(2017, 6, 20, 0, 0)
assert get_next_datetime('* * * * 3',
t) == datetime.datetime(2017, 6, 21, 0, 0)
assert get_next_datetime('* * * * 4',
t) == datetime.datetime(2017, 6, 15, 10, 17)
assert get_next_datetime('* * * * 5',
t) == datetime.datetime(2017, 6, 16, 0, 0)
assert get_next_datetime('* * * * 6',
t) == datetime.datetime(2017, 6, 17, 0, 0)
assert get_next_datetime('* * * * 7',
t) == datetime.datetime(2017, 6, 18, 0, 0)
assert get_next_datetime('* * * * mon-tue',
t) == datetime.datetime(2017, 6, 19, 0, 0)
t = datetime.datetime(2017, 6, 19, 10, 16, 50)
assert get_next_datetime('* * * * 5-6',
t) == datetime.datetime(2017, 6, 23, 0, 0)
assert get_next_datetime('* * * * 0-4',
t) == datetime.datetime(2017, 6, 19, 10, 17)
assert get_next_datetime('* * * * 5-7',
t) == datetime.datetime(2017, 6, 23, 0, 0)
assert get_next_datetime('* * * * fri-sat',
t) == datetime.datetime(2017, 6, 23, 0, 0)
assert get_next_datetime('* * * * sun-fri',
t) == datetime.datetime(2017, 6, 19, 10, 17)
assert get_next_datetime('* * * * fri-sun',
t) == datetime.datetime(2017, 6, 23, 0, 0)
assert get_next_datetime('* * * * 0-7',
t) == datetime.datetime(2017, 6, 19, 10, 17)
with pytest.raises(Exception):
get_next_datetime('* * * * wed-mon', t)
def test_impossible_dates() -> None:
t = datetime.datetime(2017, 6, 15, 10, 16, 50)
assert get_next_datetime('0 0 1 jan/2 * 2011-2013', t) is None
with pytest.raises(Exception):
get_next_datetime('* * 29 2 * 2017-2019', t)
with pytest.raises(Exception):
get_next_datetime('* * 29 2 * 2049-2050,2073-2075,2099-2101', t)
with pytest.raises(Exception):
get_next_datetime('70 * * *', t)
with pytest.raises(Exception):
get_next_datetime('* * 30 2 *', t)
with pytest.raises(Exception):
get_next_datetime('* * * * tue-mon', t)
with pytest.raises(Exception):
get_next_datetime('* * * x-dec *', t)
with pytest.raises(Exception):
get_next_datetime('* * * jan-y *', t)
with pytest.raises(Exception):
get_next_datetime('* * * nope *', t)
def test_parser() -> None:
t = datetime.datetime(2017, 6, 15, 10, 16, 50)
assert get_next_datetime('* * * * *',
t) == datetime.datetime(2017, 6, 15, 10, 17)
assert get_next_datetime('1 * * * *',
t) == datetime.datetime(2017, 6, 15, 11, 1)
assert get_next_datetime('*/2 * * * *',
t) == datetime.datetime(2017, 6, 15, 10, 18)
assert get_next_datetime('1/2 * * * *',
t) == datetime.datetime(2017, 6, 15, 10, 17)
assert get_next_datetime('1-3/2 * * * *',
t) == datetime.datetime(2017, 6, 15, 11, 1)
assert get_next_datetime('0/4 * * * *',
t) == datetime.datetime(2017, 6, 15, 10, 20)
assert get_next_datetime('7/8 * * * *',
t) == datetime.datetime(2017, 6, 15, 10, 23)
assert get_next_datetime('15 */2 * * *',
t) == datetime.datetime(2017, 6, 15, 12, 15)
assert get_next_datetime('15 */2 * * *',
t) == datetime.datetime(2017, 6, 15, 12, 15)
assert get_next_datetime('15-30 * * * *',
t) == datetime.datetime(2017, 6, 15, 10, 17)
assert get_next_datetime('20-30 * * * *',
t) == datetime.datetime(2017, 6, 15, 10, 20)
assert get_next_datetime('5,10,55 * * * *',
t) == datetime.datetime(2017, 6, 15, 10, 55)
def test_advanced_parsing() -> None:
t = datetime.datetime(2017, 6, 15, 10, 16, 50)
assert get_next_datetime('39 3 L * *',
t) == datetime.datetime(2017, 6, 30, 3, 39)
assert get_next_datetime('10-15,30,45 10 * * *',
t) == datetime.datetime(2017, 6, 15, 10, 30)
t = datetime.datetime(2017, 6, 15, 10, 12, 50)
assert get_next_datetime('10-15,30,45 10 * * *',
t) == datetime.datetime(2017, 6, 15, 10, 13)
t = datetime.datetime(2017, 6, 15, 9, 12, 50)
assert get_next_datetime('10-15,30,45 10 * * *',
t) == datetime.datetime(2017, 6, 15, 10, 10)
t = datetime.datetime(2017, 6, 15, 10, 16, 50)
assert get_next_datetime('55 7 * * Lsun',
t) == datetime.datetime(2017, 6, 25, 7, 55)
assert get_next_datetime('* * * * Lsun',
t) == datetime.datetime(2017, 6, 25)
assert get_next_datetime('* * * * Lwed-fri',
t) == datetime.datetime(2017, 6, 28)
assert get_next_datetime('* * 4-15 feb-jun wed-fri',
t) == datetime.datetime(2017, 6, 15, 10, 17)
assert get_next_datetime('3-20/2 5 4-15 feb-may *',
t) == datetime.datetime(2018, 2, 4, 5, 3)
assert get_next_datetime('3-20/2 5 4-15 feb-may wed',
t) == datetime.datetime(2018, 2, 4, 5, 3)
assert get_next_datetime('3-20/2 5 10-15 feb-may wed',
t) == datetime.datetime(2018, 2, 7, 5, 3)
assert get_next_datetime('3-20/2 5 * feb-may wed',
t) == datetime.datetime(2018, 2, 7, 5, 3)
assert get_next_datetime('3-20/2 5 4-15 feb-may mon,tue-wed',
t) == datetime.datetime(2018, 2, 4, 5, 3)
assert get_next_datetime('3-20/2 5 4-15 feb-may wed-fri',
t) == datetime.datetime(2018, 2, 1, 5, 3)
assert get_next_datetime('3-20/2 5 7-15 feb-may wed,tue,sat,mon',
t) == datetime.datetime(2018, 2, 3, 5, 3)
assert get_next_datetime('* * 29 2 *',
t) == datetime.datetime(2020, 2, 29, 0, 0)
assert get_next_datetime('* * 29 2 0',
t) == datetime.datetime(2018, 2, 4, 0, 0)
assert get_next_datetime('* * 29 2 0 2020',
t) == datetime.datetime(2020, 2, 2, 0, 0)
assert get_next_datetime('30 5 * jan,mar Ltue',
t) == datetime.datetime(2018, 1, 30, 5, 30)
t = datetime.datetime(2011, 1, 10, 23, 59, 30)
assert get_next_datetime('0 0 1 jan/2 * 2011-2013',
t) == datetime.datetime(2011, 3, 1)
t = datetime.datetime(2017, 6, 15, 10, 16, 50)
assert get_next_datetime('* * 29 2 mon 2048',
t) == datetime.datetime(2048, 2, 3, 0, 0)
assert get_next_datetime('* * 29 2 * 2048',
t) == datetime.datetime(2048, 2, 29, 0, 0)
assert get_next_datetime('* * 29 2 * 2049,2051-2060',
t) == datetime.datetime(2052, 2, 29, 0, 0)
def next_call_at(cls,
current_time: float,
interval: Optional[Union[str, int]] = None,
timestamp: Optional[str] = None,
timezone: Optional[str] = None) -> int:
if not timezone:
tz = tzlocal.get_localzone()
else:
try:
tz = pytz.timezone(timezone or '')
except Exception as e:
raise Exception('Unknown timezone: {}'.format(timezone)) from e
local_tz = tzlocal.get_localzone()
if interval is None and timestamp is not None:
if isinstance(timestamp, str):
try:
datetime_object = datetime.datetime.strptime(
timestamp, '%Y-%m-%d %H:%M:%S')
interval = '{} {} {} {} * {}'.format(
datetime_object.minute, datetime_object.hour,
datetime_object.day, datetime_object.month,
datetime_object.year)
second_modifier = 1
if tz.localize(datetime_object) > local_tz.localize(
datetime.datetime.fromtimestamp(current_time)):
second_modifier = -60
next_at = get_next_datetime(
interval,
local_tz.localize(
datetime.datetime.fromtimestamp(
current_time +
second_modifier)).astimezone(tz))
if not next_at:
return int(current_time + 60 * 60 * 24 * 365 * 100)
return int(next_at.timestamp() + datetime_object.second)
except ValueError:
pass
try:
datetime_object = datetime.datetime.strptime(
timestamp, '%Y-%m-%d %H:%M')
interval = '{} {} {} {} * {}'.format(
datetime_object.minute, datetime_object.hour,
datetime_object.day, datetime_object.month,
datetime_object.year)
next_at = get_next_datetime(
interval,
local_tz.localize(
datetime.datetime.fromtimestamp(current_time +
1)).astimezone(tz))
if not next_at:
return int(current_time + 60 * 60 * 24 * 365 * 100)
return int(next_at.timestamp())
except ValueError:
pass
try:
datetime_object = datetime.datetime.strptime(
timestamp, '%H:%M:%S')
datetime_object = datetime.datetime(
datetime.datetime.fromtimestamp(current_time).year,
datetime.datetime.fromtimestamp(current_time).month,
datetime.datetime.fromtimestamp(current_time).day,
datetime_object.hour, datetime_object.minute,
datetime_object.second)
interval = '{} {} * * *'.format(datetime_object.minute,
datetime_object.hour)
second_modifier = 1
if tz.localize(datetime_object) > local_tz.localize(
datetime.datetime.fromtimestamp(current_time)):
second_modifier = -60
next_at = get_next_datetime(
interval,
local_tz.localize(
datetime.datetime.fromtimestamp(
current_time +
second_modifier)).astimezone(tz))
if not next_at:
return int(current_time + 60 * 60 * 24 * 365 * 100)
return int(next_at.timestamp() + datetime_object.second)
except ValueError:
pass
try:
datetime_object = datetime.datetime.strptime(
timestamp, '%H:%M')
interval = '{} {} * * *'.format(datetime_object.minute,
datetime_object.hour)
next_at = get_next_datetime(
interval,
local_tz.localize(
datetime.datetime.fromtimestamp(current_time +
1)).astimezone(tz))
if not next_at:
return int(current_time + 60 * 60 * 24 * 365 * 100)
return int(next_at.timestamp())
except ValueError:
pass
raise Exception('Invalid timestamp')
if interval is not None:
if isinstance(interval, int):
return int(current_time + interval)
interval_aliases = {
('every second', '1s', '1 s', '1second', '1 second', 'second', 'secondly', 'once per second'):
1,
('every minute', '1m', '1 m', '1minute', '1 minute', 'minute', 'minutely', 'once per minute'):
'@minutely',
('every hour', '1h', '1 h', '1hour', '1 hour', 'hour', 'hourly', 'once per hour'):
'@hourly',
('every day', '1d', '1 d', '1day', '1 day', 'day', 'daily', 'once per day', 'nightly'):
'@daily',
('every month', '1month', '1 month', 'month', 'monthly', 'once per month'):
'@monthly',
('every year', '1y', '1 y', '1year', '1 year', 'year', 'yearly', 'once per year', 'annually'):
'@yearly',
('monday', 'mondays', 'mon', 'every monday', 'once per monday', 'weekly', 'once per week', 'week', 'every week'):
'0 0 * * 1',
('tuesday', 'tuesdays', 'tue', 'every tuesday', 'once per tuesday'):
'0 0 * * 2',
('wednesday', 'wednesdays', 'wed', 'every wednesday', 'once per wednesday'):
'0 0 * * 3',
('thursday', 'thursdays', 'thu', 'every thursday', 'once per thursday'):
'0 0 * * 4',
('friday', 'fridays', 'fri', 'every friday', 'once per friday'):
'0 0 * * 5',
('saturday', 'saturdays', 'sat', 'every saturday', 'once per saturday'):
'0 0 * * 6',
('sunday', 'sundays', 'sun', 'every sunday', 'once per sunday'):
'0 0 * * 0',
('weekday', 'weekdays', 'every weekday'):
'0 0 * * 1-5',
('weekend', 'weekends', 'every weekend'):
'0 0 * * 0,6'
} # type: Dict[Tuple[str, ...], Union[str, int]]
interval = interval.lower()
if interval.endswith('s') or interval.endswith('seconds'):
try:
interval = int(
interval.replace('seconds',
'').replace('s', '').replace(' ', ''))
except ValueError:
pass
try:
interval_value = [
v for k, v in interval_aliases.items() if interval in k
][0] # type: Union[str, int]
except IndexError:
interval_value = interval
if isinstance(interval_value, int):
return int(current_time + interval_value)
try:
next_at = get_next_datetime(
interval_value,
local_tz.localize(
datetime.datetime.fromtimestamp(current_time +
1)).astimezone(tz))
if not next_at:
return int(current_time + 60 * 60 * 24 * 365 * 100)
return int(next_at.timestamp())
except Exception:
raise Exception('Invalid interval')
return int(current_time + 60 * 60 * 24 * 365 * 100)
def test_isoweekday() -> None:
t = datetime.datetime(2017, 6, 15, 10, 16, 50)
assert get_next_datetime("* * * * 0",
t) == datetime.datetime(2017, 6, 18, 0, 0)
assert get_next_datetime("* * * * 1",
t) == datetime.datetime(2017, 6, 19, 0, 0)
assert get_next_datetime("* * * * 2",
t) == datetime.datetime(2017, 6, 20, 0, 0)
assert get_next_datetime("* * * * 3",
t) == datetime.datetime(2017, 6, 21, 0, 0)
assert get_next_datetime("* * * * 4",
t) == datetime.datetime(2017, 6, 15, 10, 17)
assert get_next_datetime("* * * * 5",
t) == datetime.datetime(2017, 6, 16, 0, 0)
assert get_next_datetime("* * * * 6",
t) == datetime.datetime(2017, 6, 17, 0, 0)
assert get_next_datetime("* * * * 7",
t) == datetime.datetime(2017, 6, 18, 0, 0)
assert get_next_datetime("* * * * mon-tue",
t) == datetime.datetime(2017, 6, 19, 0, 0)
t = datetime.datetime(2017, 6, 19, 10, 16, 50)
assert get_next_datetime("* * * * 5-6",
t) == datetime.datetime(2017, 6, 23, 0, 0)
assert get_next_datetime("* * * * 0-4",
t) == datetime.datetime(2017, 6, 19, 10, 17)
assert get_next_datetime("* * * * 5-7",
t) == datetime.datetime(2017, 6, 23, 0, 0)
assert get_next_datetime("* * * * fri-sat",
t) == datetime.datetime(2017, 6, 23, 0, 0)
assert get_next_datetime("* * * * sun-fri",
t) == datetime.datetime(2017, 6, 19, 10, 17)
assert get_next_datetime("* * * * fri-sun",
t) == datetime.datetime(2017, 6, 23, 0, 0)
assert get_next_datetime("* * * * 0-7",
t) == datetime.datetime(2017, 6, 19, 10, 17)
with pytest.raises(Exception):
get_next_datetime("* * * * wed-mon", t)
def test_parser() -> None:
t = datetime.datetime(2017, 6, 15, 10, 16, 50)
assert get_next_datetime("* * * * *",
t) == datetime.datetime(2017, 6, 15, 10, 17)
assert get_next_datetime("1 * * * *",
t) == datetime.datetime(2017, 6, 15, 11, 1)
assert get_next_datetime("*/2 * * * *",
t) == datetime.datetime(2017, 6, 15, 10, 18)
assert get_next_datetime("1/2 * * * *",
t) == datetime.datetime(2017, 6, 15, 10, 17)
assert get_next_datetime("1-3/2 * * * *",
t) == datetime.datetime(2017, 6, 15, 11, 1)
assert get_next_datetime("0/4 * * * *",
t) == datetime.datetime(2017, 6, 15, 10, 20)
assert get_next_datetime("7/8 * * * *",
t) == datetime.datetime(2017, 6, 15, 10, 23)
assert get_next_datetime("15 */2 * * *",
t) == datetime.datetime(2017, 6, 15, 12, 15)
assert get_next_datetime("15 */2 * * *",
t) == datetime.datetime(2017, 6, 15, 12, 15)
assert get_next_datetime("15-30 * * * *",
t) == datetime.datetime(2017, 6, 15, 10, 17)
assert get_next_datetime("20-30 * * * *",
t) == datetime.datetime(2017, 6, 15, 10, 20)
assert get_next_datetime("5,10,55 * * * *",
t) == datetime.datetime(2017, 6, 15, 10, 55)