FA-77249 / Calendar recurrence rules / Member archive

Rendering a recurrence rule as a human-readable sentence: negative ordinal · case 04

BYDAY=-1FR is rendered as "the 1st to last Friday".

Member previewVariant 4 · 3 implementations · 9 checks per implementation

Case contract

House style: "every <unit>" for interval 1, else "every <n> <unit>s"; weekday lists are in Monday-first order without duplicates and joined as "A, B and C"; the exact set MO..FR renders as "on weekdays"; an ordinal renders "on the 2nd Tuesday", -1 as "on the last Friday" and -n (n>1) as "on the 2nd to last Friday"; count renders ", once" for 1 and ", <n> times" otherwise.

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
last friday monthly	`"every month on the 1st to last Friday, 6 times"`	`"every month on the last Friday, 6 times"`	Failed

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