petl-developers / petl / 35547285936

92%

push

github

Fix tuple formatting in DuplicateKeyError and FieldSelectionError (#718)

Formatting a `DuplicateKeyError` or `FieldSelectionError` with a tuple
currently treats that tuple as the formatting argument list. Empty and
multi-element tuples raise `TypeError` during `str(error)`; a
one-element tuple loses its tuple representation.

Wrap the value in a singleton tuple so `%r` formats the whole value.
This preserves scalar messages and existing exception attributes without
changing accepted field selectors. Add regression tests for both
exception classes and the public `valuecounter` / strict `lookupone`
paths, plus a changelog entry.

Related to #641. The argument usage documentation was already clarified
by #714; this addresses the remaining exception-formatting behavior.

## Validation

Windows / Python 3.12.14, based on master 9a0b844:

- New tests against the original source: 8 failed, 6 passed.
- Targeted errors/counting/lookups tests after the fix: 33 passed.
- `python -m pytest -p no:cacheprovider -q petl/test --tb=short`: 583
passed, 17 skipped, 5 warnings.
- Same full command on the original source: 569 passed, 17 skipped, 5
warnings.

Optional dependencies and the full tox/Python-version matrix were not
tested. The change retains Python 2.7-compatible syntax, but Python 2.7
was not run locally. All three uploaded files were compared with the
locally tested files and matched.

AI assistance was used to prepare and review this patch; the reported
tests were executed locally.

20 of 20 new or added lines in 2 files covered. (100.0%)

14320 of 15545 relevant lines covered (92.12%)

0.92 hits per line