naturaltime: wrong translation with delta >= 2 years

What did you do?

Ran the following code:

import humanize
import datetime as dt

humanize.i18n.activate("fr_FR")
output = humanize.naturaltime(dt.datetime(year=2010, month=1, day=1))
print(output)

What did you expect to happen?

Output to be:

il y a 12 ans

What actually happened?

Output was:

il y a 12 years

What versions are you using?

• OS: Mac OS
• Python: 3.8.6
• Humanize: 4.0.1

[carterbox]

The general translation workflow seems to be:

1. generate possible format strings
2. translate the unevaluated format strings
3. evaluate the format strings.

When I added the intcomma feature for years in the time module, I didn’t properly test step 2 (translate the format string). Since the translation works directly on the format string and the translation phrases include the formatters (probably because in some locales the order is changed), switching from %d to %s broke the translation step. This means the translation is broken for all translated languages.

Notably, this translation error does not occur in precisedelta() because the translation and format evaluation occur on multiple lines, so the %d are swapped for %s after translation.

https://github.com/python-humanize/humanize/blob/29d37fb15945433d295b942bd839ae152770eca0/src/humanize/time.py#L564-L567

So the solution would be to match naturaldelta() with precisedelta() and swap the formatter after the translation.

I don’t want to change the translation files or swap the formatters in other places because using %d instead of %s may be used to do rounding or truncation of floating point numbers.

[hugovk]

Here’s a more direct reproducer. The first three asserts are fine, but the last fails because it get “12 years” not “12 ans”:

import humanize

output = humanize.naturaldelta(1 * 365 * 24 * 60 * 60)
print(output)
assert output == "a year"

output = humanize.naturaldelta(12 * 365 * 24 * 60 * 60)
print(output)
assert output == "12 years"


humanize.i18n.activate("fr_FR")

output = humanize.naturaldelta(1 * 365 * 24 * 60 * 60)
print(output)
assert output == "un an"

output = humanize.naturaldelta(12 * 365 * 24 * 60 * 60)
print(output)  # "12 years"
assert output == "12 ans"

This was introduced in https://github.com/python-humanize/humanize/commit/d1faf1cff76d5add3b4e9849522d8ea9a0f49d0d from PR https://github.com/jmoiron/humanize/pull/246:

Instead of passing an integer to the _ngettext localisation function we’re passing in the results of intcomma(years) which is a string:

-        return _ngettext("%d year", "%d years", years) % years
+        return _ngettext("%s year", "%s years", years) % intcomma(years)

And also I think it can’t find "%s year", "%s years" values because they use %d in the translation files:

https://github.com/python-humanize/humanize/blob/7688f204a994e55f8e607675363178e5d8424523/src/humanize/locale/fr_FR/LC_MESSAGES/humanize.po#L339-L344

Ping @carterbox, please could you have a look at this?