FAILURE MAP
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FA-3836 / Serialization / Open access

A positional template confuses zero-based argument indexes · case 01

A positional template confuses zero-based argument indexes.

Verified by executionVariant 1 · 4 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The implementation applies an operation whose text or grammar semantics violate this contract: Given two strings, render second then first separated by a slash.

VERIFIED REPAIR

Implement the complete stated contract, including the boundary fixtures: Given two strings, render second then first separated by a slash.

Unsuccessful approach: The attempted repair handles the primary example but still violates a separate boundary of the same contract.

Case contract

Given two strings, render second then first separated by a slash.

Why this case matters

A local executable model for consumers of structured text; oracle values are authored literals, not outputs copied from the repaired implementation.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
import re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct
from urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit
from email.header import decode_header, make_header
from email.utils import getaddresses
from xml.etree import ElementTree as ET
import shlex, string, textwrap

N = 1
observations = []
def solve(x):
    try:
        return '{0}/{1}'.format(*x)
    except Exception as exc:
        return {"error": type(exc).__name__}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('boundary 1', solve(['a', 'b']), 'b/a')
check('boundary 2', solve(['', 'x']), 'x/')
check('boundary 3', solve(['x', '']), '/x')
check('boundary 4', solve(['same', 'same']), 'same/same')
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 fixtureActualExpectedOutcome
boundary 1a/bb/aFailed
boundary 2/xx/Failed
boundary 3x//xFailed
boundary 4same/samesame/samePassed

SHA-256 / 107e0823e5036498c626eccc1eec778adba790d5bfe9303cc4b92f35ebe078f4

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
import re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct
from urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit
from email.header import decode_header, make_header
from email.utils import getaddresses
from xml.etree import ElementTree as ET
import shlex, string, textwrap

N = 1
observations = []
def solve(x):
    try:
        return '{1}/{1}'.format(*x)
    except Exception as exc:
        return {"error": type(exc).__name__}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('boundary 1', solve(['a', 'b']), 'b/a')
check('boundary 2', solve(['', 'x']), 'x/')
check('boundary 3', solve(['x', '']), '/x')
check('boundary 4', solve(['same', 'same']), 'same/same')
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 fixtureActualExpectedOutcome
boundary 1b/bb/aFailed
boundary 2x/xx/Failed
boundary 3//xFailed
boundary 4same/samesame/samePassed

SHA-256 / 175bb82d34e31e0ad13b51a3f2c676cd502b29f6aef1e50df4c78ec8b0d9178f

3 / The verified repair

Exit 0
"""Failure Map reference implementation. Python standard library only."""
import json
import re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct
from urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit
from email.header import decode_header, make_header
from email.utils import getaddresses
from xml.etree import ElementTree as ET
import shlex, string, textwrap

N = 1
observations = []
def solve(x):
    try:
        return '{1}/{0}'.format(*x)
    except Exception as exc:
        return {"error": type(exc).__name__}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('boundary 1', solve(['a', 'b']), 'b/a')
check('boundary 2', solve(['', 'x']), 'x/')
check('boundary 3', solve(['x', '']), '/x')
check('boundary 4', solve(['same', 'same']), 'same/same')
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 fixtureActualExpectedOutcome
boundary 1b/ab/aPassed
boundary 2x/x/Passed
boundary 3/x/xPassed
boundary 4same/samesame/samePassed

SHA-256 / 25880a4e0e6be5276f6886aed441e51b5def6a36d2d39e651ceefa25906ddbfb

Verification & scope

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 2026-09-29T14:37:31.451586+00:00.

Case digest / fe81543d6ec05a17e5a73a24e789625bcc4d7f4ef52d726459f1d3131fb8d37e