FA-76859 / Calendar recurrence rules / Member archive

Weekly BYDAY expansion honouring the week-start day: before start · case 04

Days of the first week that precede dtstart are reported as instances.

Member previewVariant 4 · 3 implementations · 7 checks per implementation

Case contract

FREQ=WEEKLY expansion. byday lists weekday numbers (0=Monday..6=Sunday); an empty list means the weekday of dtstart. Weeks begin on wkst; the week containing dtstart is week 0 and only weeks whose index is a multiple of interval are active. Instances are chronological, never before dtstart, and dtstart itself is an instance only if its weekday is listed. Return the first count ISO dates.

Why this case matters

Recurring calendar series are expanded into concrete instances for display, reminders and conflict checks.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
WKST=SU weekly SA,SU	`["2024-03-03", "2024-03-09", "2024-03-10", "2024-03-16"]`	`["2024-03-09", "2024-03-10", "2024-03-16", "2024-03-17"]`	Failed

MEMBER ARCHIVE

The complete case is available to members.

This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

Member access is invitation-based. Sign in with your invited account to inspect the sources.