FA-76936 / Calendar recurrence rules / Open access
Monthly BYSETPOS selection from a weekday set: emit order · case 01
BYSETPOS=-1,1 emits the last day before the first, and COUNT keeps the wrong instance.
ROOT CAUSE
Selected days are emitted in BYSETPOS order rather than chronologically.
VERIFIED REPAIR
At the emit order decision use `sorted(picked)`, leaving the other decision sites of the model unchanged.
Unsuccessful approach: The partial repair `picked[::-1]` reverses the position order, which is only chronological for one specific input ordering.
Case contract
FREQ=MONTHLY;BYDAY=<weekdays>;BYSETPOS=<positions>. For each month from the dtstart month, the candidate set is every day of the whole month whose weekday is listed, in date order. Positions are 1-based, negative from the end; out-of-range positions are ignored and positions naming the same day yield it once. Selected days are emitted chronologically; days before dtstart are dropped after selection. Return the first count ISO dates.
Why this case matters
Recurring calendar series are expanded into concrete instances for display, reminders and conflict checks.
1 / The failure
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import datetime as dt
import calendar
N = 1
observations = []
def solve(dtstart, weekdays, setpos, count):
start = dt.date.fromisoformat(dtstart)
out = []
for k in range(240):
mi = start.month - 1 + k
y, m = start.year + mi // 12, mi % 12 + 1
dim = calendar.monthrange(y, m)[1]
cand = [x for x in [dt.date(y, m, d) for d in range(1, dim + 1)] if x.weekday() in weekdays and x >= dt.date(y, m, 1)]
picked = []
for p in setpos:
idx = p - 1 if p > 0 else len(cand) + p
if 0 <= idx < len(cand) and cand[idx] not in picked:
picked.append(cand[idx])
for d in picked:
if d < start:
continue
out.append(d.isoformat())
if len(out) >= count:
return out
return out
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: last weekday of month',
['2024-01-01', [0, 1, 2, 3, 4], [-1], 4],
['2024-01-31', '2024-02-29', '2024-03-29', '2024-04-30']),
('first weekday, dtstart mid-month',
['2024-01-10', [0, 1, 2, 3, 4], [1], 3],
['2024-02-01', '2024-03-01', '2024-04-01']),
('first and last in reverse order',
['2024-03-01', [0, 1, 2, 3, 4], [-1, 1], 4],
['2024-03-01', '2024-03-29', '2024-04-01', '2024-04-30']),
('coinciding positions',
['2024-01-01', [0], [1, -5], 4],
['2024-01-01', '2024-02-05', '2024-03-04', '2024-04-01']),
('three positions with repeat',
['2024-04-01', [2], [1, -1, -5], 5],
['2024-04-03', '2024-04-24', '2024-05-01', '2024-05-29', '2024-06-05']),
('out of range negative', ['2024-01-01', [5, 6], [-7, 1], 3], ['2024-01-06', '2024-01-07', '2024-02-03']),
('out of range positive', ['2024-02-01', [0], [5], 3], ['2024-04-29', '2024-07-29', '2024-09-30'])],
[('first and last in reverse order',
['2024-03-01', [0, 1, 2, 3, 4], [-1, 1], 4],
['2024-03-01', '2024-03-29', '2024-04-01', '2024-04-30']),
('coinciding positions',
['2024-01-01', [0], [1, -5], 4],
['2024-01-01', '2024-02-05', '2024-03-04', '2024-04-01']),
('three positions with repeat',
['2024-04-01', [2], [1, -1, -5], 5],
['2024-04-03', '2024-04-24', '2024-05-01', '2024-05-29', '2024-06-05']),
('out of range negative', ['2024-01-01', [5, 6], [-7, 1], 3], ['2024-01-06', '2024-01-07', '2024-02-03']),
('out of range positive', ['2024-02-01', [0], [5], 3], ['2024-04-29', '2024-07-29', '2024-09-30']),
('second weekend day', ['2024-06-15', [5, 6], [2], 3], ['2024-07-07', '2024-08-04', '2024-09-07']),
('second to last weekday',
['2024-07-01', [0, 1, 2, 3, 4], [-2], 3],
['2024-07-30', '2024-08-29', '2024-09-27'])],
[('three positions with repeat',
['2024-04-01', [2], [1, -1, -5], 5],
['2024-04-03', '2024-04-24', '2024-05-01', '2024-05-29', '2024-06-05']),
('out of range negative', ['2024-01-01', [5, 6], [-7, 1], 3], ['2024-01-06', '2024-01-07', '2024-02-03']),
('out of range positive', ['2024-02-01', [0], [5], 3], ['2024-04-29', '2024-07-29', '2024-09-30']),
('second weekend day', ['2024-06-15', [5, 6], [2], 3], ['2024-07-07', '2024-08-04', '2024-09-07']),
('second to last weekday',
['2024-07-01', [0, 1, 2, 3, 4], [-2], 3],
['2024-07-30', '2024-08-29', '2024-09-27']),
('position 3 of TU,TH mid month',
['2024-09-12', [1, 3], [3, -1], 4],
['2024-09-26', '2024-10-08', '2024-10-31', '2024-11-12']),
('december rollover',
['2024-12-01', [4], [1, -1], 4],
['2024-12-06', '2024-12-27', '2025-01-03', '2025-01-31'])],
[('out of range positive', ['2024-02-01', [0], [5], 3], ['2024-04-29', '2024-07-29', '2024-09-30']),
('second weekend day', ['2024-06-15', [5, 6], [2], 3], ['2024-07-07', '2024-08-04', '2024-09-07']),
('second to last weekday',
['2024-07-01', [0, 1, 2, 3, 4], [-2], 3],
['2024-07-30', '2024-08-29', '2024-09-27']),
('position 3 of TU,TH mid month',
['2024-09-12', [1, 3], [3, -1], 4],
['2024-09-26', '2024-10-08', '2024-10-31', '2024-11-12']),
('december rollover',
['2024-12-01', [4], [1, -1], 4],
['2024-12-06', '2024-12-27', '2025-01-03', '2025-01-31']),
('dtstart equals picked day', ['2024-05-31', [0, 1, 2, 3, 4], [-1], 2], ['2024-05-31', '2024-06-28']),
('regression: last weekday of month',
['2024-01-01', [0, 1, 2, 3, 4], [-1], 4],
['2024-01-31', '2024-02-29', '2024-03-29', '2024-04-30']),
('out of range negative', ['2024-01-01', [5, 6], [-7, 1], 3], ['2024-01-06', '2024-01-07', '2024-02-03'])],
[('second to last weekday',
['2024-07-01', [0, 1, 2, 3, 4], [-2], 3],
['2024-07-30', '2024-08-29', '2024-09-27']),
('position 3 of TU,TH mid month',
['2024-09-12', [1, 3], [3, -1], 4],
['2024-09-26', '2024-10-08', '2024-10-31', '2024-11-12']),
('december rollover',
['2024-12-01', [4], [1, -1], 4],
['2024-12-06', '2024-12-27', '2025-01-03', '2025-01-31']),
('dtstart equals picked day', ['2024-05-31', [0, 1, 2, 3, 4], [-1], 2], ['2024-05-31', '2024-06-28']),
('regression: last weekday of month',
['2024-01-01', [0, 1, 2, 3, 4], [-1], 4],
['2024-01-31', '2024-02-29', '2024-03-29', '2024-04-30']),
('first weekday, dtstart mid-month',
['2024-01-10', [0, 1, 2, 3, 4], [1], 3],
['2024-02-01', '2024-03-01', '2024-04-01']),
('first and last in reverse order',
['2024-03-01', [0, 1, 2, 3, 4], [-1, 1], 4],
['2024-03-01', '2024-03-29', '2024-04-01', '2024-04-30'])]]
for label, args, expected in fixtures[N-1]:
check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| regression: last weekday of month | ['2024-01-31', '2024-02-29', '2024-03-29', '2024-04-30'] | ['2024-01-31', '2024-02-29', '2024-03-29', '2024-04-30'] | Passed |
| first weekday, dtstart mid-month | ['2024-02-01', '2024-03-01', '2024-04-01'] | ['2024-02-01', '2024-03-01', '2024-04-01'] | Passed |
| first and last in reverse order | ['2024-03-29', '2024-03-01', '2024-04-30', '2024-04-01'] | ['2024-03-01', '2024-03-29', '2024-04-01', '2024-04-30'] | Failed |
| coinciding positions | ['2024-01-01', '2024-02-05', '2024-03-04', '2024-04-01'] | ['2024-01-01', '2024-02-05', '2024-03-04', '2024-04-01'] | Passed |
| three positions with repeat | ['2024-04-03', '2024-04-24', '2024-05-01', '2024-05-29', '2024-06-05'] | ['2024-04-03', '2024-04-24', '2024-05-01', '2024-05-29', '2024-06-05'] | Passed |
| out of range negative | ['2024-01-07', '2024-01-06', '2024-02-04'] | ['2024-01-06', '2024-01-07', '2024-02-03'] | Failed |
| out of range positive | ['2024-04-29', '2024-07-29', '2024-09-30'] | ['2024-04-29', '2024-07-29', '2024-09-30'] | Passed |
SHA-256 / 0e94e89d69bc9f8b7ae62c55a8ae9339f9f88f06389cb393b4cd77d13b6aa1b7
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import datetime as dt
import calendar
N = 1
observations = []
def solve(dtstart, weekdays, setpos, count):
start = dt.date.fromisoformat(dtstart)
out = []
for k in range(240):
mi = start.month - 1 + k
y, m = start.year + mi // 12, mi % 12 + 1
dim = calendar.monthrange(y, m)[1]
cand = [x for x in [dt.date(y, m, d) for d in range(1, dim + 1)] if x.weekday() in weekdays and x >= dt.date(y, m, 1)]
picked = []
for p in setpos:
idx = p - 1 if p > 0 else len(cand) + p
if 0 <= idx < len(cand) and cand[idx] not in picked:
picked.append(cand[idx])
for d in picked[::-1]:
if d < start:
continue
out.append(d.isoformat())
if len(out) >= count:
return out
return out
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: last weekday of month',
['2024-01-01', [0, 1, 2, 3, 4], [-1], 4],
['2024-01-31', '2024-02-29', '2024-03-29', '2024-04-30']),
('first weekday, dtstart mid-month',
['2024-01-10', [0, 1, 2, 3, 4], [1], 3],
['2024-02-01', '2024-03-01', '2024-04-01']),
('first and last in reverse order',
['2024-03-01', [0, 1, 2, 3, 4], [-1, 1], 4],
['2024-03-01', '2024-03-29', '2024-04-01', '2024-04-30']),
('coinciding positions',
['2024-01-01', [0], [1, -5], 4],
['2024-01-01', '2024-02-05', '2024-03-04', '2024-04-01']),
('three positions with repeat',
['2024-04-01', [2], [1, -1, -5], 5],
['2024-04-03', '2024-04-24', '2024-05-01', '2024-05-29', '2024-06-05']),
('out of range negative', ['2024-01-01', [5, 6], [-7, 1], 3], ['2024-01-06', '2024-01-07', '2024-02-03']),
('out of range positive', ['2024-02-01', [0], [5], 3], ['2024-04-29', '2024-07-29', '2024-09-30'])],
[('first and last in reverse order',
['2024-03-01', [0, 1, 2, 3, 4], [-1, 1], 4],
['2024-03-01', '2024-03-29', '2024-04-01', '2024-04-30']),
('coinciding positions',
['2024-01-01', [0], [1, -5], 4],
['2024-01-01', '2024-02-05', '2024-03-04', '2024-04-01']),
('three positions with repeat',
['2024-04-01', [2], [1, -1, -5], 5],
['2024-04-03', '2024-04-24', '2024-05-01', '2024-05-29', '2024-06-05']),
('out of range negative', ['2024-01-01', [5, 6], [-7, 1], 3], ['2024-01-06', '2024-01-07', '2024-02-03']),
('out of range positive', ['2024-02-01', [0], [5], 3], ['2024-04-29', '2024-07-29', '2024-09-30']),
('second weekend day', ['2024-06-15', [5, 6], [2], 3], ['2024-07-07', '2024-08-04', '2024-09-07']),
('second to last weekday',
['2024-07-01', [0, 1, 2, 3, 4], [-2], 3],
['2024-07-30', '2024-08-29', '2024-09-27'])],
[('three positions with repeat',
['2024-04-01', [2], [1, -1, -5], 5],
['2024-04-03', '2024-04-24', '2024-05-01', '2024-05-29', '2024-06-05']),
('out of range negative', ['2024-01-01', [5, 6], [-7, 1], 3], ['2024-01-06', '2024-01-07', '2024-02-03']),
('out of range positive', ['2024-02-01', [0], [5], 3], ['2024-04-29', '2024-07-29', '2024-09-30']),
('second weekend day', ['2024-06-15', [5, 6], [2], 3], ['2024-07-07', '2024-08-04', '2024-09-07']),
('second to last weekday',
['2024-07-01', [0, 1, 2, 3, 4], [-2], 3],
['2024-07-30', '2024-08-29', '2024-09-27']),
('position 3 of TU,TH mid month',
['2024-09-12', [1, 3], [3, -1], 4],
['2024-09-26', '2024-10-08', '2024-10-31', '2024-11-12']),
('december rollover',
['2024-12-01', [4], [1, -1], 4],
['2024-12-06', '2024-12-27', '2025-01-03', '2025-01-31'])],
[('out of range positive', ['2024-02-01', [0], [5], 3], ['2024-04-29', '2024-07-29', '2024-09-30']),
('second weekend day', ['2024-06-15', [5, 6], [2], 3], ['2024-07-07', '2024-08-04', '2024-09-07']),
('second to last weekday',
['2024-07-01', [0, 1, 2, 3, 4], [-2], 3],
['2024-07-30', '2024-08-29', '2024-09-27']),
('position 3 of TU,TH mid month',
['2024-09-12', [1, 3], [3, -1], 4],
['2024-09-26', '2024-10-08', '2024-10-31', '2024-11-12']),
('december rollover',
['2024-12-01', [4], [1, -1], 4],
['2024-12-06', '2024-12-27', '2025-01-03', '2025-01-31']),
('dtstart equals picked day', ['2024-05-31', [0, 1, 2, 3, 4], [-1], 2], ['2024-05-31', '2024-06-28']),
('regression: last weekday of month',
['2024-01-01', [0, 1, 2, 3, 4], [-1], 4],
['2024-01-31', '2024-02-29', '2024-03-29', '2024-04-30']),
('out of range negative', ['2024-01-01', [5, 6], [-7, 1], 3], ['2024-01-06', '2024-01-07', '2024-02-03'])],
[('second to last weekday',
['2024-07-01', [0, 1, 2, 3, 4], [-2], 3],
['2024-07-30', '2024-08-29', '2024-09-27']),
('position 3 of TU,TH mid month',
['2024-09-12', [1, 3], [3, -1], 4],
['2024-09-26', '2024-10-08', '2024-10-31', '2024-11-12']),
('december rollover',
['2024-12-01', [4], [1, -1], 4],
['2024-12-06', '2024-12-27', '2025-01-03', '2025-01-31']),
('dtstart equals picked day', ['2024-05-31', [0, 1, 2, 3, 4], [-1], 2], ['2024-05-31', '2024-06-28']),
('regression: last weekday of month',
['2024-01-01', [0, 1, 2, 3, 4], [-1], 4],
['2024-01-31', '2024-02-29', '2024-03-29', '2024-04-30']),
('first weekday, dtstart mid-month',
['2024-01-10', [0, 1, 2, 3, 4], [1], 3],
['2024-02-01', '2024-03-01', '2024-04-01']),
('first and last in reverse order',
['2024-03-01', [0, 1, 2, 3, 4], [-1, 1], 4],
['2024-03-01', '2024-03-29', '2024-04-01', '2024-04-30'])]]
for label, args, expected in fixtures[N-1]:
check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| regression: last weekday of month | ['2024-01-31', '2024-02-29', '2024-03-29', '2024-04-30'] | ['2024-01-31', '2024-02-29', '2024-03-29', '2024-04-30'] | Passed |
| first weekday, dtstart mid-month | ['2024-02-01', '2024-03-01', '2024-04-01'] | ['2024-02-01', '2024-03-01', '2024-04-01'] | Passed |
| first and last in reverse order | ['2024-03-01', '2024-03-29', '2024-04-01', '2024-04-30'] | ['2024-03-01', '2024-03-29', '2024-04-01', '2024-04-30'] | Passed |
| coinciding positions | ['2024-01-01', '2024-02-05', '2024-03-04', '2024-04-01'] | ['2024-01-01', '2024-02-05', '2024-03-04', '2024-04-01'] | Passed |
| three positions with repeat | ['2024-04-24', '2024-04-03', '2024-05-29', '2024-05-01', '2024-06-26'] | ['2024-04-03', '2024-04-24', '2024-05-01', '2024-05-29', '2024-06-05'] | Failed |
| out of range negative | ['2024-01-06', '2024-01-07', '2024-02-03'] | ['2024-01-06', '2024-01-07', '2024-02-03'] | Passed |
| out of range positive | ['2024-04-29', '2024-07-29', '2024-09-30'] | ['2024-04-29', '2024-07-29', '2024-09-30'] | Passed |
SHA-256 / 0cba3eb13bf76b060336f8120130359f90838787babf8a7ab8d5b0c865ba6c2c
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
import datetime as dt
import calendar
N = 1
observations = []
def solve(dtstart, weekdays, setpos, count):
start = dt.date.fromisoformat(dtstart)
out = []
for k in range(240):
mi = start.month - 1 + k
y, m = start.year + mi // 12, mi % 12 + 1
dim = calendar.monthrange(y, m)[1]
cand = [x for x in [dt.date(y, m, d) for d in range(1, dim + 1)] if x.weekday() in weekdays and x >= dt.date(y, m, 1)]
picked = []
for p in setpos:
idx = p - 1 if p > 0 else len(cand) + p
if 0 <= idx < len(cand) and cand[idx] not in picked:
picked.append(cand[idx])
for d in sorted(picked):
if d < start:
continue
out.append(d.isoformat())
if len(out) >= count:
return out
return out
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: last weekday of month',
['2024-01-01', [0, 1, 2, 3, 4], [-1], 4],
['2024-01-31', '2024-02-29', '2024-03-29', '2024-04-30']),
('first weekday, dtstart mid-month',
['2024-01-10', [0, 1, 2, 3, 4], [1], 3],
['2024-02-01', '2024-03-01', '2024-04-01']),
('first and last in reverse order',
['2024-03-01', [0, 1, 2, 3, 4], [-1, 1], 4],
['2024-03-01', '2024-03-29', '2024-04-01', '2024-04-30']),
('coinciding positions',
['2024-01-01', [0], [1, -5], 4],
['2024-01-01', '2024-02-05', '2024-03-04', '2024-04-01']),
('three positions with repeat',
['2024-04-01', [2], [1, -1, -5], 5],
['2024-04-03', '2024-04-24', '2024-05-01', '2024-05-29', '2024-06-05']),
('out of range negative', ['2024-01-01', [5, 6], [-7, 1], 3], ['2024-01-06', '2024-01-07', '2024-02-03']),
('out of range positive', ['2024-02-01', [0], [5], 3], ['2024-04-29', '2024-07-29', '2024-09-30'])],
[('first and last in reverse order',
['2024-03-01', [0, 1, 2, 3, 4], [-1, 1], 4],
['2024-03-01', '2024-03-29', '2024-04-01', '2024-04-30']),
('coinciding positions',
['2024-01-01', [0], [1, -5], 4],
['2024-01-01', '2024-02-05', '2024-03-04', '2024-04-01']),
('three positions with repeat',
['2024-04-01', [2], [1, -1, -5], 5],
['2024-04-03', '2024-04-24', '2024-05-01', '2024-05-29', '2024-06-05']),
('out of range negative', ['2024-01-01', [5, 6], [-7, 1], 3], ['2024-01-06', '2024-01-07', '2024-02-03']),
('out of range positive', ['2024-02-01', [0], [5], 3], ['2024-04-29', '2024-07-29', '2024-09-30']),
('second weekend day', ['2024-06-15', [5, 6], [2], 3], ['2024-07-07', '2024-08-04', '2024-09-07']),
('second to last weekday',
['2024-07-01', [0, 1, 2, 3, 4], [-2], 3],
['2024-07-30', '2024-08-29', '2024-09-27'])],
[('three positions with repeat',
['2024-04-01', [2], [1, -1, -5], 5],
['2024-04-03', '2024-04-24', '2024-05-01', '2024-05-29', '2024-06-05']),
('out of range negative', ['2024-01-01', [5, 6], [-7, 1], 3], ['2024-01-06', '2024-01-07', '2024-02-03']),
('out of range positive', ['2024-02-01', [0], [5], 3], ['2024-04-29', '2024-07-29', '2024-09-30']),
('second weekend day', ['2024-06-15', [5, 6], [2], 3], ['2024-07-07', '2024-08-04', '2024-09-07']),
('second to last weekday',
['2024-07-01', [0, 1, 2, 3, 4], [-2], 3],
['2024-07-30', '2024-08-29', '2024-09-27']),
('position 3 of TU,TH mid month',
['2024-09-12', [1, 3], [3, -1], 4],
['2024-09-26', '2024-10-08', '2024-10-31', '2024-11-12']),
('december rollover',
['2024-12-01', [4], [1, -1], 4],
['2024-12-06', '2024-12-27', '2025-01-03', '2025-01-31'])],
[('out of range positive', ['2024-02-01', [0], [5], 3], ['2024-04-29', '2024-07-29', '2024-09-30']),
('second weekend day', ['2024-06-15', [5, 6], [2], 3], ['2024-07-07', '2024-08-04', '2024-09-07']),
('second to last weekday',
['2024-07-01', [0, 1, 2, 3, 4], [-2], 3],
['2024-07-30', '2024-08-29', '2024-09-27']),
('position 3 of TU,TH mid month',
['2024-09-12', [1, 3], [3, -1], 4],
['2024-09-26', '2024-10-08', '2024-10-31', '2024-11-12']),
('december rollover',
['2024-12-01', [4], [1, -1], 4],
['2024-12-06', '2024-12-27', '2025-01-03', '2025-01-31']),
('dtstart equals picked day', ['2024-05-31', [0, 1, 2, 3, 4], [-1], 2], ['2024-05-31', '2024-06-28']),
('regression: last weekday of month',
['2024-01-01', [0, 1, 2, 3, 4], [-1], 4],
['2024-01-31', '2024-02-29', '2024-03-29', '2024-04-30']),
('out of range negative', ['2024-01-01', [5, 6], [-7, 1], 3], ['2024-01-06', '2024-01-07', '2024-02-03'])],
[('second to last weekday',
['2024-07-01', [0, 1, 2, 3, 4], [-2], 3],
['2024-07-30', '2024-08-29', '2024-09-27']),
('position 3 of TU,TH mid month',
['2024-09-12', [1, 3], [3, -1], 4],
['2024-09-26', '2024-10-08', '2024-10-31', '2024-11-12']),
('december rollover',
['2024-12-01', [4], [1, -1], 4],
['2024-12-06', '2024-12-27', '2025-01-03', '2025-01-31']),
('dtstart equals picked day', ['2024-05-31', [0, 1, 2, 3, 4], [-1], 2], ['2024-05-31', '2024-06-28']),
('regression: last weekday of month',
['2024-01-01', [0, 1, 2, 3, 4], [-1], 4],
['2024-01-31', '2024-02-29', '2024-03-29', '2024-04-30']),
('first weekday, dtstart mid-month',
['2024-01-10', [0, 1, 2, 3, 4], [1], 3],
['2024-02-01', '2024-03-01', '2024-04-01']),
('first and last in reverse order',
['2024-03-01', [0, 1, 2, 3, 4], [-1, 1], 4],
['2024-03-01', '2024-03-29', '2024-04-01', '2024-04-30'])]]
for label, args, expected in fixtures[N-1]:
check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| regression: last weekday of month | ['2024-01-31', '2024-02-29', '2024-03-29', '2024-04-30'] | ['2024-01-31', '2024-02-29', '2024-03-29', '2024-04-30'] | Passed |
| first weekday, dtstart mid-month | ['2024-02-01', '2024-03-01', '2024-04-01'] | ['2024-02-01', '2024-03-01', '2024-04-01'] | Passed |
| first and last in reverse order | ['2024-03-01', '2024-03-29', '2024-04-01', '2024-04-30'] | ['2024-03-01', '2024-03-29', '2024-04-01', '2024-04-30'] | Passed |
| coinciding positions | ['2024-01-01', '2024-02-05', '2024-03-04', '2024-04-01'] | ['2024-01-01', '2024-02-05', '2024-03-04', '2024-04-01'] | Passed |
| three positions with repeat | ['2024-04-03', '2024-04-24', '2024-05-01', '2024-05-29', '2024-06-05'] | ['2024-04-03', '2024-04-24', '2024-05-01', '2024-05-29', '2024-06-05'] | Passed |
| out of range negative | ['2024-01-06', '2024-01-07', '2024-02-03'] | ['2024-01-06', '2024-01-07', '2024-02-03'] | Passed |
| out of range positive | ['2024-04-29', '2024-07-29', '2024-09-30'] | ['2024-04-29', '2024-07-29', '2024-09-30'] | Passed |
SHA-256 / 4966e7b8632bf7c5412fbfc98be3b4ca5ee1a8d5bdc20123117bc5039c37c1d7
Verification & scope
Stipulated, bounded recurrence-expansion model evaluated offline on explicit fixtures; it is not a complete iCalendar implementation and makes no claim of standards conformance. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.
Observations recorded using Python 3.12.14 at 2026-09-29T14:49:20.977578+00:00.
Case digest / f17b2f4af11cd0b5e5dbbfd132939a333a8fbd74dea360acfb2ce70935c6f930