Reject non-positive date_range steps

[CodingFeng101]

Summary

Reject date_range() steps that do not advance the generated date. Passing values such as months=0 or days=-1 currently allows the generator to yield the start date and then continue without making forward progress, which can hang callers that consume the full iterator with list(...).

Changes

• Add a positive-step validation in dateparser.date.date_range().
• Add a focused regression test for zero-month and negative-day steps.

Validation

• python -m pytest tests/test_date_range.py -q -> 2 passed
• Manual smoke check confirmed normal daily and monthly ranges still produce the same forward dates.

[AdrianAtZyte]

Does Python’s range implement any kind of validation like this, or does it leave it up to the user to pass the right value?

[CodingFeng101]

Thanks for checking. Python's range() validates the one case that cannot make progress: range(..., step=0) raises ValueError: range() arg 3 must not be zero. It allows negative steps because range() has explicit backward-iteration semantics when the caller provides matching start/stop values.

My thinking here was that date_range() currently advances from begin toward end, and non-positive deltas such as months=0 or days=-1 can make the generator fail to progress toward that end in common calls like list(date_range(begin, end, months=0)). So the validation is meant to fail early for non-progressing steps instead of leaving callers with an accidental infinite iterator.

That said, if you prefer to leave this to callers or want an issue first before changing this behavior, I understand and am happy to close the PR.

[AdrianAtZyte]

Could you move this to the existing TestDateRangeFunction?

[CodingFeng101]

Moved it into the existing TestDateRangeFunction in 4cbea3a and removed the separate test file.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.11%. Comparing base (08c78d3) to head (4cbea3a).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1339   +/-   ##
=======================================
  Coverage   97.11%   97.11%           
=======================================
  Files         235      235           
  Lines        2909     2911    +2     
=======================================
+ Hits         2825     2827    +2     
  Misses         84       84           

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[AdrianAtZyte]

Please, run pre-commit run --all-files.

[CodingFeng101]

Ran pre-commit run --all-files. ruff-format reformatted the new date range test in 1150f2f, and a second run now passes:

ruff.....................................................................Passed
ruff-format..............................................................Passed

I also ran git diff --check, which passed. I tried rerunning python -m pytest tests/test_date.py::TestDateRangeFunction -q locally, but on Windows collection fails before reaching the test because tests/test_date.py imports time.tzset, which is not available on Windows.