[arin30]

diff_files() leaves both argparse-opened input files open after reading them. They also remain open if either JSON document fails to parse. This makes repeated in-process calls depend on garbage collection to release descriptors and file locks.

Use ExitStack to close both owned inputs after loading the documents, including on parsing errors. Standard input is left open when either filename is '-'. Output and exit codes are unchanged.

Three tests retain real input handles and check cleanup for equal and differing documents, malformed JSON in either file, and stdin in either position. All six subcases fail on unchanged master and pass with the fix.

Validation on Python 3.12.14: 289 tests and 24 property-based tests pass, the CI Flake8 error check passes, and git diff --check is clean.

[Copilot]

🟢 Approval recommended

No active review issues block approval of the input-file cleanup change.

No open issues 🎉

What changed in this PR

This PR fixes input-file cleanup in the jsondiff CLI, releasing file handles after loading documents even when JSON parsing fails.

Changes:

• Uses ExitStack to close both owned inputs while leaving standard input open.
• Adds regression tests for equal and differing documents, malformed JSON in either file, and stdin in either position.
• Preserves existing output and exit-code behavior.

File	Description
tests.py	Adds input cleanup and stdin preservation tests.
jsonpatch_cli.py	Closes owned input files after loading, including on parsing errors.

_{Review effort: Balanced}

[coveralls]

coverage: 100.0%. remained the same — arin30:fix/jsondiff-close-inputs into stefankoegl:master