Inconsistency in unix_time handling start and end time parameters

There is an inconsistency the way Faker handles unix_time() when parameter start_datetime is provided as ‘now’. start_datetime is parsed using class method _parse_start_datetime https://github.com/joke2k/faker/blob/6db5503cf070c0b09da8e98cd662c10230cea22f/faker/providers/date_time/__init__.py#L1374

which is eventually parsed by _parse_date_time, which can take argument ‘now’. When ‘now’ is the provided, datetime.now , which will use local time, https://github.com/joke2k/faker/blob/6db5503cf070c0b09da8e98cd662c10230cea22f/faker/providers/date_time/__init__.py#L1525

However, end time parameter is parsed by _parse_end_datetime, which uses time.time(). time.time() returns time since epoc ie it is utc timestamp. https://github.com/joke2k/faker/blob/6db5503cf070c0b09da8e98cd662c10230cea22f/faker/providers/date_time/__init__.py#L1477

on machines with negetive time offset, faker will run into problems because of this inconsistancy. Example

>>> import faker
>>> f = faker.Faker()
>>> f.unix_time(start_datetime='-6h')
1555352053
>>> f.unix_time(start_datetime='now')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.7/dist-packages/faker/providers/date_time/__init__.py", line 1376, in unix_time
    return self.generator.random.randint(start_datetime, end_datetime)
  File "/usr/lib/python3.7/random.py", line 222, in randint
    return self.randrange(a, b+1)
  File "/usr/lib/python3.7/random.py", line 200, in randrange
    raise ValueError("empty range for randrange() (%d,%d, %d)" % (istart, istop, width))
*ValueError: empty range for randrange() (1555373558,1555353759, -19799)*
>>>

Perhaps ‘now’ should be utcnow here https://github.com/joke2k/faker/blob/6db5503cf070c0b09da8e98cd662c10230cea22f/faker/providers/date_time/__init__.py#L1525

[fcurella]

Yes, closed with #965

[bluesheeptoken]

No worries, I have done it, was just a notification to remember to close this issue 😃.

Thanks for noticing the 🐛