[Zhuyuyangyy]

Summary

Return the integer representation "0" for exact zero in fractional, consistent with the function's whole-number formatting contract.

Currently both fractional(0) and fractional(0.0) return "0/1". The fix checks the already-converted float for exact zero before computing the fraction. Other values retain their existing truncation and denominator-limit behavior; for example, a nonzero 0.0001 still formats as "0/1" after approximation.

Tests cover integer, float, negative and string zero, plus positive/negative whole numbers, fractions, string inputs and approximation controls. The docstring and usage page include the zero example.

Local validation

• New focused cases against the old implementation: 4 failures, 10 passes.
• Patched numbers suite: 42 passed.
• Full pytest suite with the declared pytest-mock/freezegun test dependencies available: 403 passed.
• Numbers docstring examples: 11 passed.
• Ruff lint/format, mypy on the changed Python files, and git diff --check passed.

This is local Python 3.12 validation; the Nox multi-Python matrix and upstream CI have not been run by this contribution.

Disclosure: this contribution was prepared and checked with AI assistance on behalf of the account owner. It has not received an independent human review.