Low Test Coverage: utils/format-percentage.ts

[gitauto-for-dev]

Resolves #604

Summary

Add comprehensive unit tests for utils/format-percentage.ts to reach 100% line, statement, function, and branch coverage.

Test Patterns

• Formats typical numeric inputs to percentage strings (integers and decimals)
• Rounding behavior at common thresholds (e.g., 0.5 up/down) and specified precision (if supported)
• Boundary values: 0, 1, 100, and very small/large numbers
• Negative values formatting and sign handling
• Behavior for out-of-range inputs (e.g., <0, >100 or >1 depending on implementation), including clamping vs. pass-through (as implemented)
• Handling of invalid inputs: NaN, Infinity, null/undefined, non-number types; verifies thrown errors or fallbacks as implemented
• Trailing zeros behavior and precision options (if supported)
• Idempotency with already-formatted strings (e.g., inputs containing “%”), when applicable
• Ensures all conditional branches and edge cases in utils/format-percentage.ts are executed and asserted

git fetch origin
git checkout gitauto-wes/issue-604-20260118-181442-Dong
git pull origin gitauto-wes/issue-604-20260118-181442-Dong