FA-6494 / Calendar arithmetic / Member archive

Days until next year exclusive · case 04

A fixed ordinary-year length also excludes the current day incorrectly.

Member previewVariant 4 · 3 implementations · 4 checks per implementation

Case contract

Valid ISO Gregorian dates in years 1 through 9999; generated dates must remain in that range. Month is 1 through 12 and zero-based weekday is Monday 0 through Sunday 6 unless the output convention says otherwise. The input year is <=9998; count elapsed days until January 1 of the following year. Exact operational definition: (date(date.fromisoformat(text).year+1,1,1)-date.fromisoformat(text)).days

Why this case matters

Small exact fixtures expose this error without platform timing, external services, or probabilistic observations. Calendar conventions results depend on the stated convention.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
fixture 1: ('2024-12-31',)	`-1`	`1`	Failed

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