FA-6553 / Calendar arithmetic / Member archive

Weekday count half open date range · case 03

Weekend days are counted as working weekdays.

Member previewVariant 3 · 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. start<=end; count Monday through Friday in [start,end), without public-holiday exclusions. Exact operational definition: sum((date.fromisoformat(start)+timedelta(days=i)).weekday()<5 for i in range((date.fromisoformat(end)-date.fromisoformat(start)).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: ('2024-01-01', '2024-01-08')	`7`	`5`	Failed

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