Negative amounts of time result in a day from naturaldelta

[couling]

What did you do?

from humanize import naturaldelta
from datetime import datetime

print(naturaldelta(datetime.now() - datetime.now()))

What did you expect to happen?

a moment

Or some reasonable representation of the tiny amount of time between two consecutive now() calls.

What actually happened?

a day

What versions are you using?

• OS: Macos
• Python: 3.10
• Humanize: 4.9.0

[hugovk]

Hmm, this is because, when we get the delta between them both here:

humanize/src/humanize/time.py

Lines 131 to 132 in b1e5d43

	if isinstance(value, dt.timedelta):
	delta = value

It's really something like:

delta=datetime.timedelta(days=-1, seconds=86399, microseconds=999999)

This looks quite strange, and the docs explain:

String representations of timedelta objects are normalized similarly to their internal representation. This leads to somewhat unusual results for negative timedeltas. For example:

>>> timedelta(hours=-5)
datetime.timedelta(days=-1, seconds=68400)
>>> print(_)
-1 day, 19:00:00

However, we're assuming this oddness doesn't happen and find the absolute values of some delta components:

humanize/src/humanize/time.py

Lines 142 to 143 in b1e5d43

	seconds = abs(delta.seconds)
	days = abs(delta.days)

When we do abs(day), it must be because we don't really care if the delta as a whole is positive or negative. We assume all components have the same sign. But we fall into this oddness trap.

And then days < 1 is false:

humanize/src/humanize/time.py

Line 148 in b1e5d43

if not years and days < 1:

And abs(delta.days) == days == 1 is true, so return "a day":

humanize/src/humanize/time.py

Lines 186 to 188 in b1e5d43

	elif years == 0:
	if days == 1:
	return _("a day")

Really, we should have gone into the first if.

I think doing delta = abs(delta) instead of, or just before, the other abs calls might fix it.

[couling]

abs certainly helped in the examples I found:

print(naturaldelta(abs(datetime.now() - datetime.now())))

That seemed to be a valid work-around for the time being.