Fixit cli doesn't return non-zero exit code upon exceptions - add --exit-non-zero / --exit-zero options

[zyv]

Hello,

Commands like

python -m fixit.cli.apply_fix

can fail for some files in the CI silently and there is no way to detect it via the exit code - parsing also cannot be done reliably:

Encountered the following error while parsing source code in file /home/runner/work/xxx.py:
Syntax Error @ 59:19.
Incomplete input. Encountered 'operation', but expected ';', or 'NEWLINE'.

Linters like flake8 exit with non-zero code per default and they have an option like --exit-zero to ignore errors. Formatter black has option --check.

I would suggest to make fixit fail is some exception happens per default and add --exit-zero to opt out. Otherwise one can make this an opt-in functionality like --exit-non-zero.

I think this is quite important, especially after LibCST parser update, because problems can easily go unnoticed, if the is no way to make fixit return a non-zero code upon errors.

Thanks!

[zyv]

Thank you @amyreese !

[samueljsb]

This issue appears to have regressed:

$ cat t.py
this is not valid python

$ fixit fix -a t.py
t.py: EXCEPTION: Syntax Error @ 1:1.
parser error: error at 1:24: expected one of !=, %, &, (, *, **, +, ,, -, ., /, //, ;, <, <<, <=, ==, >, >=, >>, @, NEWLINE, [, ^, and, if, in, is, not, or, |

this is not valid python
^
Traceback (most recent call last):
  File "/private/tmp/tmpvenv-c329d/venv/lib/python3.11/site-packages/fixit/api.py", line 100, in fixit_bytes
    runner = LintRunner(path, content)
             ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/private/tmp/tmpvenv-c329d/venv/lib/python3.11/site-packages/fixit/engine.py", line 55, in __init__
    self.module: Module = parse_module(source)
                          ^^^^^^^^^^^^^^^^^^^^
  File "/private/tmp/tmpvenv-c329d/venv/lib/python3.11/site-packages/libcst/_parser/entrypoints.py", line 109, in parse_module
    result = _parse(
             ^^^^^^^
  File "/private/tmp/tmpvenv-c329d/venv/lib/python3.11/site-packages/libcst/_parser/entrypoints.py", line 55, in _parse
    return parse(source_str)
           ^^^^^^^^^^^^^^^^^
libcst._exceptions.ParserSyntaxError: Syntax Error @ 1:1.
parser error: error at 1:24: expected one of !=, %, &, (, *, **, +, ,, -, ., /, //, ;, <, <<, <=, ==, >, >=, >>, @, NEWLINE, [, ^, and, if, in, is, not, or, |

this is not valid python
^
🛠️  1 file checked, 1 file with errors 🛠️

$ echo $?
0

Fixit version 2.1.0, Python 3.11.5 (main, Aug 24 2023, 15:09:45) [Clang 14.0.3 (clang-1403.0.22.14.1)].