fix: pluralize function signature and test update

[eslteacher902010]

This PR improves test coverage and clarity for three utility functions:

pluralize: Updated signature to take both a count and singular word, defaulting to appending "s" when appropriate.

parse_requires: Added tests to validate parsing of multiline requirement strings.

is_dir_writable: Added cross-platform tests for directory writability, including permission errors and missing directories.

These changes fix test mismatches, improve clarity, and increase overall reliability of Poetry’s helper functions.

[sourcery-ai]

Reviewer's Guide

Refactors the pluralize helper to use a clear (count, singular) signature with logic to append “s” for non-unit counts and updates tests accordingly to resolve existing failures.

File-Level Changes

Change	Details	Files
Refactor pluralize signature and logic	Changed function signature to accept (count, singular) Updated branching to return singular when count == 1 and append “s” otherwise Preserved behavior when singular is an empty string	poetry/utils/helpers.py
Add and adjust tests for new signature	Imported pluralize into test_helpers Added test_pluralize with assertions for counts 0, 1, 2, and empty singular	tests/utils/test_helpers.py

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[sourcery-ai]

Hey @eslteacher902010 - I've reviewed your changes and they look great!

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[radoering]

I did not even know that such a function exists. 😅

Can you please use pytest.mark.parametrize instead of calling the function multiple times in the test.

And please take a look at the failing pre-commit.ci. See also https://python-poetry.org/docs/contributing/#local-development

[eslteacher902010]

I did not even know that such a function exists. 😅

Can you please use pytest.mark.parametrize instead of calling the function multiple times in the test.

And please take a look at the failing pre-commit.ci. See also https://python-poetry.org/docs/contributing/#local-development

Thanks for the feedback! I removed the obsolete test_shell.py (now that I understand the shell logic lives in a plugin) and added a test file for the helper functions (pluralize, is_dir_writable, and parse_requires). I also updated the tests to use pytest.mark.parametrize where appropriate. Let me know if there’s anything else I should tweak!