FA-66406 / Airline fare rule evaluation / Open access

Last day of a season excluded · case 01

Travel on 31 August falls out of the summer season.

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ROOT CAUSE

The non-wrapping range test excludes the end date.

THE FAILURE

The non-wrapping range test excludes the end date.

Unsuccessful approach: Moving the exclusion to the start date drops the first day of each season instead.

Case contract

Input {'date','seasons':[[start 'M-D', end 'M-D' (unpadded allowed), weekdays string of ISO digits 1=Mon..7=Sun, code]]}. A season with start after end wraps the year end. Both ends inclusive. Return the code of the first season (list order) containing the date on an allowed weekday, else 'NONE'.

Why this case matters

Fare seasonality tables use month-day ranges that can wrap the year boundary and are further restricted by day of week.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import datetime
N = 1
observations = []
def solve(x):
    d = datetime.date.fromisoformat(x['date'])
    md = (d.month, d.day)
    for start, end, dow, code in x['seasons']:
        s = tuple(int(p) for p in start.split('-'))
        e = tuple(int(p) for p in end.split('-'))
        inside = s <= md < e if s <= e else (md >= s or md <= e)
        if inside and str(d.isoweekday()) in dow:
            return code
    return 'NONE'
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['New Year inside wrap season', {'date': '2028-01-03', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'PEAK'], ['season end day', {'date': '2027-08-31', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'HIGH_WK'], ['Sunday in summer', {'date': '2027-07-04', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'HIGH_WE'], ['autumn weekday', {'date': '2027-10-05', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'SHOULDER'], ['wrap end date', {'date': '2029-01-10', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'PEAK'], ['overlapping seasons first wins', {'date': '2027-12-20', 'seasons': [['12-1', '12-31', '1234567', 'DEC'], ['12-15', '1-10', '1234567', 'PEAK']]}, 'DEC'], ['two-digit month compare', {'date': '2027-10-13', 'seasons': [['9-1', '11-30', '1234567', 'FALL'], ['3-1', '5-31', '1234567', 'SPRING']]}, 'FALL'], ['sampled case 1', {'date': '2029-02-24', 'seasons': [['10-27', '3-18', '257', 'S0'], ['10-8', '11-12', '2346', 'S1'], ['3-2', '4-14', '23467', 'S2']]}, 'NONE'], ['sampled case 2', {'date': '2029-09-07', 'seasons': [['12-12', '5-9', '123456', 'S0'], ['12-8', '2-16', '1234567', 'S1'], ['6-10', '10-12', '12347', 'S2']]}, 'NONE'], ['sampled case 3', {'date': '2029-03-20', 'seasons': [['7-27', '9-9', '123567', 'S0'], ['10-31', '12-13', '1357', 'S1']]}, 'NONE'], ['regression: season end inclusion', {'date': '2027-05-18', 'seasons': [['5-18', '8-21', '2346', 'S0'], ['4-13', '6-8', '123457', 'S1'], ['6-14', '9-30', '12457', 'S2']]}, 'S0']], [['New Year inside wrap season', {'date': '2028-01-04', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'PEAK'], ['season end day', {'date': '2027-08-31', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'HIGH_WK'], ['Sunday in summer', {'date': '2027-07-11', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'HIGH_WE'], ['autumn weekday', {'date': '2027-10-06', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'SHOULDER'], ['wrap end date', {'date': '2029-01-10', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'PEAK'], ['overlapping seasons first wins', {'date': '2027-12-20', 'seasons': [['12-1', '12-31', '1234567', 'DEC'], ['12-15', '1-10', '1234567', 'PEAK']]}, 'DEC'], ['two-digit month compare', {'date': '2027-10-14', 'seasons': [['9-1', '11-30', '1234567', 'FALL'], ['3-1', '5-31', '1234567', 'SPRING']]}, 'FALL'], ['sampled case 1', {'date': '2029-05-03', 'seasons': [['5-4', '7-25', '13457', 'S0'], ['6-18', '9-12', '1234567', 'S1'], ['2-7', '6-1', '3', 'S2']]}, 'NONE'], ['sampled case 2', {'date': '2027-05-20', 'seasons': [['8-18', '2-4', '17', 'S0'], ['12-23', '12-28', '1267', 'S1']]}, 'NONE'], ['sampled case 3', {'date': '2028-01-27', 'seasons': [['2-5', '2-6', '136', 'S0'], ['11-22', '3-11', '23', 'S1'], ['10-29', '11-15', '67', 'S2'], ['4-23', '6-13', '1367', 'S3']]}, 'NONE'], ['regression: season end inclusion', {'date': '2028-01-10', 'seasons': [['4-4', '9-8', '27', 'S0'], ['9-11', '1-19', '5', 'S1'], ['10-26', '5-6', '23457', 'S2'], ['1-10', '2-24', '1234567', 'S3']]}, 'S3']], [['New Year inside wrap season', {'date': '2028-01-05', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'PEAK'], ['season end day', {'date': '2027-08-31', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'HIGH_WK'], ['Sunday in summer', {'date': '2027-07-18', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'HIGH_WE'], ['autumn weekday', {'date': '2027-10-07', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'SHOULDER'], ['wrap end date', {'date': '2029-01-10', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'PEAK'], ['overlapping seasons first wins', {'date': '2027-12-20', 'seasons': [['12-1', '12-31', '1234567', 'DEC'], ['12-15', '1-10', '1234567', 'PEAK']]}, 'DEC'], ['two-digit month compare', {'date': '2027-10-15', 'seasons': [['9-1', '11-30', '1234567', 'FALL'], ['3-1', '5-31', '1234567', 'SPRING']]}, 'FALL'], ['sampled case 1', {'date': '2028-09-07', 'seasons': [['12-12', '3-3', '15', 'S0'], ['4-5', '4-30', '6', 'S1'], ['12-10', '1-5', '136', 'S2']]}, 'NONE'], ['sampled case 2', {'date': '2027-08-20', 'seasons': [['10-3', '2-23', '137', 'S0']]}, 'NONE'], ['sampled case 3', {'date': '2029-01-15', 'seasons': [['1-2', '5-8', '16', 'S0'], ['1-19', '6-11', '1234567', 'S1'], ['10-17', '1-6', '2456', 'S2'], ['11-19', '1-26', '34567', 'S3']]}, 'S0'], ['regression: season end inclusion', {'date': '2029-06-28', 'seasons': [['6-28', '8-7', '1234567', 'S0'], ['11-13', '3-26', '12567', 'S1'], ['3-23', '6-28', '134567', 'S2'], ['6-13', '10-6', '1234567', 'S3']]}, 'S0']], [['New Year inside wrap season', {'date': '2028-01-06', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'PEAK'], ['season end day', {'date': '2027-08-31', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'HIGH_WK'], ['Sunday in summer', {'date': '2027-07-25', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'HIGH_WE'], ['autumn weekday', {'date': '2027-10-08', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'NONE'], ['wrap end date', {'date': '2029-01-10', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'PEAK'], ['overlapping seasons first wins', {'date': '2027-12-20', 'seasons': [['12-1', '12-31', '1234567', 'DEC'], ['12-15', '1-10', '1234567', 'PEAK']]}, 'DEC'], ['two-digit month compare', {'date': '2027-10-16', 'seasons': [['9-1', '11-30', '1234567', 'FALL'], ['3-1', '5-31', '1234567', 'SPRING']]}, 'FALL'], ['sampled case 1', {'date': '2028-03-30', 'seasons': [['1-26', '6-22', '4', 'S0'], ['5-16', '8-21', '123467', 'S1'], ['8-21', '11-24', '123467', 'S2'], ['2-13', '7-22', '1246', 'S3']]}, 'S0'], ['sampled case 2', {'date': '2029-03-23', 'seasons': [['9-11', '3-12', '1234', 'S0']]}, 'NONE'], ['sampled case 3', {'date': '2029-03-01', 'seasons': [['4-26', '5-25', '1234567', 'S0'], ['10-24', '12-15', '7', 'S1'], ['10-4', '3-14', '1246', 'S2']]}, 'S2'], ['regression: season end inclusion', {'date': '2027-04-16', 'seasons': [['11-13', '5-8', '7', 'S0'], ['1-6', '7-23', '2346', 'S1'], ['4-23', '9-25', '123567', 'S2'], ['4-16', '7-18', '123567', 'S3']]}, 'S3']], [['New Year inside wrap season', {'date': '2028-01-07', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'PEAK'], ['season end day', {'date': '2027-08-31', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'HIGH_WK'], ['Sunday in summer', {'date': '2027-07-04', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'HIGH_WE'], ['autumn weekday', {'date': '2027-10-09', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'NONE'], ['wrap end date', {'date': '2029-01-10', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'PEAK'], ['overlapping seasons first wins', {'date': '2027-12-20', 'seasons': [['12-1', '12-31', '1234567', 'DEC'], ['12-15', '1-10', '1234567', 'PEAK']]}, 'DEC'], ['two-digit month compare', {'date': '2027-10-17', 'seasons': [['9-1', '11-30', '1234567', 'FALL'], ['3-1', '5-31', '1234567', 'SPRING']]}, 'FALL'], ['sampled case 1', {'date': '2029-04-07', 'seasons': [['12-9', '5-18', '123456', 'S0'], ['11-27', '12-4', '12457', 'S1']]}, 'S0'], ['sampled case 2', {'date': '2027-10-12', 'seasons': [['7-20', '1-2', '4', 'S0']]}, 'NONE'], ['sampled case 3', {'date': '2027-06-11', 'seasons': [['9-12', '2-18', '46', 'S0'], ['1-5', '7-14', '4', 'S1'], ['3-28', '6-4', '1234567', 'S2'], ['8-26', '9-24', '123567', 'S3']]}, 'NONE'], ['regression: season end inclusion', {'date': '2027-08-05', 'seasons': [['11-12', '3-23', '1234567', 'S0'], ['8-5', '8-20', '1234567', 'S1']]}, 'S1']]]
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
New Year inside wrap season	`PEAK`	`PEAK`	Passed
season end day	`NONE`	`HIGH_WK`	Failed
Sunday in summer	`HIGH_WE`	`HIGH_WE`	Passed
autumn weekday	`SHOULDER`	`SHOULDER`	Passed
wrap end date	`PEAK`	`PEAK`	Passed
overlapping seasons first wins	`DEC`	`DEC`	Passed
two-digit month compare	`FALL`	`FALL`	Passed
sampled case 1	`NONE`	`NONE`	Passed
sampled case 2	`NONE`	`NONE`	Passed
sampled case 3	`NONE`	`NONE`	Passed
regression: season end inclusion	`S0`	`S0`	Passed

SHA-256 / f4f2e0d3c73df802ba4bab9484417f267936496c3b88a7652b034065163a42a8

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import datetime
N = 1
observations = []
def solve(x):
    d = datetime.date.fromisoformat(x['date'])
    md = (d.month, d.day)
    for start, end, dow, code in x['seasons']:
        s = tuple(int(p) for p in start.split('-'))
        e = tuple(int(p) for p in end.split('-'))
        inside = s < md <= e if s <= e else (md >= s or md <= e)
        if inside and str(d.isoweekday()) in dow:
            return code
    return 'NONE'
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['New Year inside wrap season', {'date': '2028-01-03', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'PEAK'], ['season end day', {'date': '2027-08-31', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'HIGH_WK'], ['Sunday in summer', {'date': '2027-07-04', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'HIGH_WE'], ['autumn weekday', {'date': '2027-10-05', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'SHOULDER'], ['wrap end date', {'date': '2029-01-10', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'PEAK'], ['overlapping seasons first wins', {'date': '2027-12-20', 'seasons': [['12-1', '12-31', '1234567', 'DEC'], ['12-15', '1-10', '1234567', 'PEAK']]}, 'DEC'], ['two-digit month compare', {'date': '2027-10-13', 'seasons': [['9-1', '11-30', '1234567', 'FALL'], ['3-1', '5-31', '1234567', 'SPRING']]}, 'FALL'], ['sampled case 1', {'date': '2029-02-24', 'seasons': [['10-27', '3-18', '257', 'S0'], ['10-8', '11-12', '2346', 'S1'], ['3-2', '4-14', '23467', 'S2']]}, 'NONE'], ['sampled case 2', {'date': '2029-09-07', 'seasons': [['12-12', '5-9', '123456', 'S0'], ['12-8', '2-16', '1234567', 'S1'], ['6-10', '10-12', '12347', 'S2']]}, 'NONE'], ['sampled case 3', {'date': '2029-03-20', 'seasons': [['7-27', '9-9', '123567', 'S0'], ['10-31', '12-13', '1357', 'S1']]}, 'NONE'], ['regression: season end inclusion', {'date': '2027-05-18', 'seasons': [['5-18', '8-21', '2346', 'S0'], ['4-13', '6-8', '123457', 'S1'], ['6-14', '9-30', '12457', 'S2']]}, 'S0']], [['New Year inside wrap season', {'date': '2028-01-04', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'PEAK'], ['season end day', {'date': '2027-08-31', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'HIGH_WK'], ['Sunday in summer', {'date': '2027-07-11', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'HIGH_WE'], ['autumn weekday', {'date': '2027-10-06', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'SHOULDER'], ['wrap end date', {'date': '2029-01-10', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'PEAK'], ['overlapping seasons first wins', {'date': '2027-12-20', 'seasons': [['12-1', '12-31', '1234567', 'DEC'], ['12-15', '1-10', '1234567', 'PEAK']]}, 'DEC'], ['two-digit month compare', {'date': '2027-10-14', 'seasons': [['9-1', '11-30', '1234567', 'FALL'], ['3-1', '5-31', '1234567', 'SPRING']]}, 'FALL'], ['sampled case 1', {'date': '2029-05-03', 'seasons': [['5-4', '7-25', '13457', 'S0'], ['6-18', '9-12', '1234567', 'S1'], ['2-7', '6-1', '3', 'S2']]}, 'NONE'], ['sampled case 2', {'date': '2027-05-20', 'seasons': [['8-18', '2-4', '17', 'S0'], ['12-23', '12-28', '1267', 'S1']]}, 'NONE'], ['sampled case 3', {'date': '2028-01-27', 'seasons': [['2-5', '2-6', '136', 'S0'], ['11-22', '3-11', '23', 'S1'], ['10-29', '11-15', '67', 'S2'], ['4-23', '6-13', '1367', 'S3']]}, 'NONE'], ['regression: season end inclusion', {'date': '2028-01-10', 'seasons': [['4-4', '9-8', '27', 'S0'], ['9-11', '1-19', '5', 'S1'], ['10-26', '5-6', '23457', 'S2'], ['1-10', '2-24', '1234567', 'S3']]}, 'S3']], [['New Year inside wrap season', {'date': '2028-01-05', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'PEAK'], ['season end day', {'date': '2027-08-31', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'HIGH_WK'], ['Sunday in summer', {'date': '2027-07-18', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'HIGH_WE'], ['autumn weekday', {'date': '2027-10-07', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'SHOULDER'], ['wrap end date', {'date': '2029-01-10', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'PEAK'], ['overlapping seasons first wins', {'date': '2027-12-20', 'seasons': [['12-1', '12-31', '1234567', 'DEC'], ['12-15', '1-10', '1234567', 'PEAK']]}, 'DEC'], ['two-digit month compare', {'date': '2027-10-15', 'seasons': [['9-1', '11-30', '1234567', 'FALL'], ['3-1', '5-31', '1234567', 'SPRING']]}, 'FALL'], ['sampled case 1', {'date': '2028-09-07', 'seasons': [['12-12', '3-3', '15', 'S0'], ['4-5', '4-30', '6', 'S1'], ['12-10', '1-5', '136', 'S2']]}, 'NONE'], ['sampled case 2', {'date': '2027-08-20', 'seasons': [['10-3', '2-23', '137', 'S0']]}, 'NONE'], ['sampled case 3', {'date': '2029-01-15', 'seasons': [['1-2', '5-8', '16', 'S0'], ['1-19', '6-11', '1234567', 'S1'], ['10-17', '1-6', '2456', 'S2'], ['11-19', '1-26', '34567', 'S3']]}, 'S0'], ['regression: season end inclusion', {'date': '2029-06-28', 'seasons': [['6-28', '8-7', '1234567', 'S0'], ['11-13', '3-26', '12567', 'S1'], ['3-23', '6-28', '134567', 'S2'], ['6-13', '10-6', '1234567', 'S3']]}, 'S0']], [['New Year inside wrap season', {'date': '2028-01-06', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'PEAK'], ['season end day', {'date': '2027-08-31', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'HIGH_WK'], ['Sunday in summer', {'date': '2027-07-25', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'HIGH_WE'], ['autumn weekday', {'date': '2027-10-08', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'NONE'], ['wrap end date', {'date': '2029-01-10', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'PEAK'], ['overlapping seasons first wins', {'date': '2027-12-20', 'seasons': [['12-1', '12-31', '1234567', 'DEC'], ['12-15', '1-10', '1234567', 'PEAK']]}, 'DEC'], ['two-digit month compare', {'date': '2027-10-16', 'seasons': [['9-1', '11-30', '1234567', 'FALL'], ['3-1', '5-31', '1234567', 'SPRING']]}, 'FALL'], ['sampled case 1', {'date': '2028-03-30', 'seasons': [['1-26', '6-22', '4', 'S0'], ['5-16', '8-21', '123467', 'S1'], ['8-21', '11-24', '123467', 'S2'], ['2-13', '7-22', '1246', 'S3']]}, 'S0'], ['sampled case 2', {'date': '2029-03-23', 'seasons': [['9-11', '3-12', '1234', 'S0']]}, 'NONE'], ['sampled case 3', {'date': '2029-03-01', 'seasons': [['4-26', '5-25', '1234567', 'S0'], ['10-24', '12-15', '7', 'S1'], ['10-4', '3-14', '1246', 'S2']]}, 'S2'], ['regression: season end inclusion', {'date': '2027-04-16', 'seasons': [['11-13', '5-8', '7', 'S0'], ['1-6', '7-23', '2346', 'S1'], ['4-23', '9-25', '123567', 'S2'], ['4-16', '7-18', '123567', 'S3']]}, 'S3']], [['New Year inside wrap season', {'date': '2028-01-07', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'PEAK'], ['season end day', {'date': '2027-08-31', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'HIGH_WK'], ['Sunday in summer', {'date': '2027-07-04', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'HIGH_WE'], ['autumn weekday', {'date': '2027-10-09', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'NONE'], ['wrap end date', {'date': '2029-01-10', 'seasons': [['12-15', '1-10', '1234567', 'PEAK'], ['6-1', '8-31', '12345', 'HIGH_WK'], ['6-1', '8-31', '67', 'HIGH_WE'], ['1-11', '5-31', '1234567', 'LOW'], ['9-1', '12-14', '1234', 'SHOULDER']]}, 'PEAK'], ['overlapping seasons first wins', {'date': '2027-12-20', 'seasons': [['12-1', '12-31', '1234567', 'DEC'], ['12-15', '1-10', '1234567', 'PEAK']]}, 'DEC'], ['two-digit month compare', {'date': '2027-10-17', 'seasons': [['9-1', '11-30', '1234567', 'FALL'], ['3-1', '5-31', '1234567', 'SPRING']]}, 'FALL'], ['sampled case 1', {'date': '2029-04-07', 'seasons': [['12-9', '5-18', '123456', 'S0'], ['11-27', '12-4', '12457', 'S1']]}, 'S0'], ['sampled case 2', {'date': '2027-10-12', 'seasons': [['7-20', '1-2', '4', 'S0']]}, 'NONE'], ['sampled case 3', {'date': '2027-06-11', 'seasons': [['9-12', '2-18', '46', 'S0'], ['1-5', '7-14', '4', 'S1'], ['3-28', '6-4', '1234567', 'S2'], ['8-26', '9-24', '123567', 'S3']]}, 'NONE'], ['regression: season end inclusion', {'date': '2027-08-05', 'seasons': [['11-12', '3-23', '1234567', 'S0'], ['8-5', '8-20', '1234567', 'S1']]}, 'S1']]]
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
New Year inside wrap season	`PEAK`	`PEAK`	Passed
season end day	`HIGH_WK`	`HIGH_WK`	Passed
Sunday in summer	`HIGH_WE`	`HIGH_WE`	Passed
autumn weekday	`SHOULDER`	`SHOULDER`	Passed
wrap end date	`PEAK`	`PEAK`	Passed
overlapping seasons first wins	`DEC`	`DEC`	Passed
two-digit month compare	`FALL`	`FALL`	Passed
sampled case 1	`NONE`	`NONE`	Passed
sampled case 2	`NONE`	`NONE`	Passed
sampled case 3	`NONE`	`NONE`	Passed
regression: season end inclusion	`S1`	`S0`	Failed

SHA-256 / b6f45e24926d2f44755b87ca73d988f1f2429599d9fb040e5c008da471a01a19

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 11 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

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Verification & scope

A stipulated toy fare-rule contract with invented constants; it is not an ATPCO or carrier tariff implementation and makes no claim of industry-standard 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 2026-09-29T14:47:43.425573+00:00.

Case digest / 3eaaa1ee11dcd55df86dba40e169d1e565c9a4236553557a75a59ff8576e08ec