FA-48776 / Delimited text / Open access
Chunk draining splits at the final newline instead of the first · case 01
A structured table violates the declared record or column contract.
ROOT CAUSE
Chunk draining splits at the final newline instead of the first.
VERIFIED REPAIR
Preserve the named invariant at the faulty decision: record,carry=carry.split('\n',1)
Unsuccessful approach: The alternate implementation still violates the same declared invariant: chunk draining splits at the final newline instead of the first.
Case contract
Consume arbitrary text chunks of an unquoted LF-delimited table. Complete records emit immediately into an output list; carry partial records across chunks. EOF emits a nonempty remaining fragment, but not a phantom row after final LF. Empty complete physical records are retained. Return comma-split rows.
Why this case matters
Delimited interchange needs explicit framing, schema and field semantics at ingestion and emission boundaries.
1 / The failure
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
def _vary(value):
if value == '@END': return 3 + 4*N
if isinstance(value, str): return value.replace('@', 'cell' * N)
if isinstance(value, list): return [_vary(x) for x in value]
if isinstance(value, dict): return {_vary(k): _vary(v) for k,v in value.items()}
return value
N = 1
observations = []
def solve(data):
rows=[]; carry=''
for chunk in data:
carry+=chunk
while '\n' in carry:
record,carry=carry.rsplit('\n',1)
rows.append(record.split(','))
if carry: rows.append(carry.split(','))
return rows
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('split cell', solve(_vary(['a,', '@', '\nx,y\n'])), _vary([['a', '@'], ['x', 'y']]))
check('several per chunk', solve(_vary(['a,b\n@,z\n'])), _vary([['a', 'b'], ['@', 'z']]))
check('empty chunks', solve(_vary(['', '@', '', '\n', ''])), _vary([['@']]))
check('partial final', solve(_vary(['a,b\n@'])), _vary([['a', 'b'], ['@']]))
check('empty rows', solve(_vary(['\n\n'])), _vary([[''], ['']]))
check('empty input', solve(_vary([])), _vary([]))
check('no newline', solve(_vary(['@'])), _vary([['@']]))
check('split delimiter', solve(_vary(['a', '\n', 'b'])), _vary([['a'], ['b']]))
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 |
|---|---|---|---|
| split cell | [['a', 'cell\nx', 'y']] | [['a', 'cell'], ['x', 'y']] | Failed |
| several per chunk | [['a', 'b\ncell', 'z']] | [['a', 'b'], ['cell', 'z']] | Failed |
| empty chunks | [['cell']] | [['cell']] | Passed |
| partial final | [['a', 'b'], ['cell']] | [['a', 'b'], ['cell']] | Passed |
| empty rows | [['\n']] | [[''], ['']] | Failed |
| empty input | [] | [] | Passed |
| no newline | [['cell']] | [['cell']] | Passed |
| split delimiter | [['a'], ['b']] | [['a'], ['b']] | Passed |
SHA-256 / 0c14bbb32c34c10cd11127e1b76c1c46bfe3767671ab287b775219f5584bb7d2
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
def _vary(value):
if value == '@END': return 3 + 4*N
if isinstance(value, str): return value.replace('@', 'cell' * N)
if isinstance(value, list): return [_vary(x) for x in value]
if isinstance(value, dict): return {_vary(k): _vary(v) for k,v in value.items()}
return value
N = 1
observations = []
def solve(data):
rows=[]; carry=''
for chunk in data:
carry+=chunk
while '\n' in carry:
record,carry=carry.split('\n',1)[::-1]
rows.append(record.split(','))
if carry: rows.append(carry.split(','))
return rows
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('split cell', solve(_vary(['a,', '@', '\nx,y\n'])), _vary([['a', '@'], ['x', 'y']]))
check('several per chunk', solve(_vary(['a,b\n@,z\n'])), _vary([['a', 'b'], ['@', 'z']]))
check('empty chunks', solve(_vary(['', '@', '', '\n', ''])), _vary([['@']]))
check('partial final', solve(_vary(['a,b\n@'])), _vary([['a', 'b'], ['@']]))
check('empty rows', solve(_vary(['\n\n'])), _vary([[''], ['']]))
check('empty input', solve(_vary([])), _vary([]))
check('no newline', solve(_vary(['@'])), _vary([['@']]))
check('split delimiter', solve(_vary(['a', '\n', 'b'])), _vary([['a'], ['b']]))
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 |
|---|---|---|---|
| split cell | [['x', 'y\n'], ['a', 'cell']] | [['a', 'cell'], ['x', 'y']] | Failed |
| several per chunk | [['cell', 'z\n'], ['a', 'b']] | [['a', 'b'], ['cell', 'z']] | Failed |
| empty chunks | [[''], ['cell']] | [['cell']] | Failed |
| partial final | [['cell'], ['a', 'b']] | [['a', 'b'], ['cell']] | Failed |
| empty rows | [['\n']] | [[''], ['']] | Failed |
| empty input | [] | [] | Passed |
| no newline | [['cell']] | [['cell']] | Passed |
| split delimiter | [[''], ['ab']] | [['a'], ['b']] | Failed |
SHA-256 / e6c76daa0c70738ad9e0c8affff1c24d4c2441b1b2482842fb1c081fb2ceb2d8
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
def _vary(value):
if value == '@END': return 3 + 4*N
if isinstance(value, str): return value.replace('@', 'cell' * N)
if isinstance(value, list): return [_vary(x) for x in value]
if isinstance(value, dict): return {_vary(k): _vary(v) for k,v in value.items()}
return value
N = 1
observations = []
def solve(data):
rows=[]; carry=''
for chunk in data:
carry+=chunk
while '\n' in carry:
record,carry=carry.split('\n',1)
rows.append(record.split(','))
if carry: rows.append(carry.split(','))
return rows
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('split cell', solve(_vary(['a,', '@', '\nx,y\n'])), _vary([['a', '@'], ['x', 'y']]))
check('several per chunk', solve(_vary(['a,b\n@,z\n'])), _vary([['a', 'b'], ['@', 'z']]))
check('empty chunks', solve(_vary(['', '@', '', '\n', ''])), _vary([['@']]))
check('partial final', solve(_vary(['a,b\n@'])), _vary([['a', 'b'], ['@']]))
check('empty rows', solve(_vary(['\n\n'])), _vary([[''], ['']]))
check('empty input', solve(_vary([])), _vary([]))
check('no newline', solve(_vary(['@'])), _vary([['@']]))
check('split delimiter', solve(_vary(['a', '\n', 'b'])), _vary([['a'], ['b']]))
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 |
|---|---|---|---|
| split cell | [['a', 'cell'], ['x', 'y']] | [['a', 'cell'], ['x', 'y']] | Passed |
| several per chunk | [['a', 'b'], ['cell', 'z']] | [['a', 'b'], ['cell', 'z']] | Passed |
| empty chunks | [['cell']] | [['cell']] | Passed |
| partial final | [['a', 'b'], ['cell']] | [['a', 'b'], ['cell']] | Passed |
| empty rows | [[''], ['']] | [[''], ['']] | Passed |
| empty input | [] | [] | Passed |
| no newline | [['cell']] | [['cell']] | Passed |
| split delimiter | [['a'], ['b']] | [['a'], ['b']] | Passed |
SHA-256 / 85410585cfb2fad32494d3b27709ac40176364ac6f648ab54678ed08bd179c6b
Verification & scope
Deterministic bounded in-memory model. No claim of complete CSV or external format 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 2026-09-29T14:44:53.814602+00:00.
Case digest / b1402706262d606e07302233e673d4eebbf5ee802e797d9ec31babb54f802951