Mutmut 3.3.0 stalls during mutant generation

[CyberiaResurrection]

Mutmut version: 3.3.0
Python version: 3.9.21
OS: Fedora Linux 41

Repo: https://github.com/makhidkarun/traveller_pyroute

pyproject.toml bits:

[tool.mutmut]
paths_to_mutate = ["PyRoute/Outputs/SubsectorMap.py"]
tests_dir = ["Tests/"]
runner = "pytest -x"

After installing mutmut and launching it with mutmut run, mutmut launches, prints "Generating mutants" and then just sits there until I kill the process, whether a minute or an hour later.

Plain pytest runs to completion, as I thought it might be an issue with pytest config, but it doesn't look like it.

What am I doing wrong?

EDIT:
Setting the paths_to_mutate to ["PyRoute/Outputs/Colour.py"] (which doesn't seem to generate any mutants) resulted in mutant generation being done in 22 milliseconds, stats run being done, clean test run is done, and the forced fail test fails with "FAILED: Unable to force test failures"

[Otto-AA]

Can you run it with debug=true in pyproject.toml and --max-children 1? Then it should print out for which file it is currently generating mutants and you'll know where it gets stuck. Also you could check the stacktrace when doing Ctrl+C, I think this should point to the stuck code.

Maybe it's an issue with libcst getting stuck, I think I have time to look at it tomorrow.

And "paths_to_mutate" is supposed to be a list of the root directories of your code, not individual files. Likely PyRoute in your case.

[CyberiaResurrection]

@Otto-AA , I'm trying that now. I don't want to mutate the entire codebase now (although, as you've divined, that is an ultimate aim) because of this problem.

With your suggestions for config and run, I get:

(venv) alex@localhost:~/gitstuf/traveller_pyroute$ mutmut run --max-children 1
⠋ Generating mutantsPyRoute/Outputs/SubsectorMap.py
mutants/PyRoute/Outputs/SubsectorMap.py has invalid syntax:  (unicode error) 'unicodeescape' codec can't decode bytes in position 0-5: truncated \UXXXXXXXX escape (<unknown>, line 45803)

The unmutated code in question:

        if star.tradeCode.asteroid:
            worldCharacter = '\u2059'    # HERE
            size = self._get_text_size(self.fonts['hexes3'], worldCharacter)

The mutated code in question:

        if star.tradeCode.asteroid:
            worldCharacter = '\U2059'  # HERE
            size = self._get_text_size(self.fonts['hexes3'], worldCharacter)

[CyberiaResurrection]

@Otto-AA , it looks like (when trying to mutate all of PyRoute/) that whatever is generating mutants is generating the odd syntactically-invalid mutant (such as in the unicode codepoints above, or '\N' instead of '\n'.

The same run, across all of PyRoute/ has resulted in:

(venv) alex@localhost:~/gitstuf/traveller_pyroute$ mutmut run --max-children 1
⠋ Generating mutantsPyRoute/route.py
mutants/PyRoute/route.py has invalid syntax:  (unicode error) 'unicodeescape' codec can't decode bytes in position 0-1: malformed \N character escape (<unknown>, line 100385)
PyRoute/Pathfinding/RouteLandmarkGraph.py
PyRoute/Pathfinding/astar_numpy_fallback.py
PyRoute/Pathfinding/LandmarkSchemes/LandmarksTriaxialExtremes.py
PyRoute/Pathfinding/LandmarkSchemes/LandmarksWTNExtremes.py
PyRoute/Pathfinding/LandmarkSchemes/LandmarksQExtremes.py
PyRoute/Pathfinding/LandmarkSchemes/LandmarksSExtremes.py
PyRoute/Pathfinding/LandmarkSchemes/LandmarksRExtremes.py
PyRoute/Pathfinding/LandmarkSchemes/LandmarkAvoidHelper.py
PyRoute/DeltaDebug/__init__.py
PyRoute/DeltaDebug/DeltaLogicError.py
PyRoute/DeltaDebug/DeltaReduce.py
PyRoute/DeltaDebug/DeltaGalaxy.py
PyRoute/DeltaDebug/DeltaDebug.py
mutants/PyRoute/DeltaDebug/DeltaDebug.py has invalid syntax:  (unicode error) 'unicodeescape' codec can't decode bytes in position 0-1: malformed \N character escape (<unknown>, line 144117)
PyRoute/Inputs/StarlineStationTransformer.py
PyRoute/Inputs/BaseTransformer.py
mutants/PyRoute/Inputs/BaseTransformer.py has invalid syntax:  (unicode error) 'unicodeescape' codec can't decode bytes in position 0-1: malformed \N character escape (<unknown>, line 123)
PyRoute/DeltaPasses/SingleLineReducer.py
PyRoute/DeltaPasses/WidenHoleReducer.py
PyRoute/DeltaPasses/SubsectorReducer.py
PyRoute/DeltaPasses/ZoneTrimLineReduce.py
PyRoute/DeltaPasses/ZoneLineReduce.py
PyRoute/DeltaPasses/AuxiliaryLineReduce.py
PyRoute/DeltaPasses/AllegianceReducer.py
PyRoute/DeltaPasses/BaseLineReduce.py
PyRoute/DeltaPasses/TradeCodeTrimLineReduce.py
PyRoute/DeltaPasses/Canonicalisation.py
mutants/PyRoute/DeltaPasses/Canonicalisation.py has invalid syntax:  (unicode error) 'unicodeescape' codec can't decode bytes in position 175-176: malformed \N character escape (<unknown>, line 1507)

It's been stalled on the Canonicalisation invalid-syntax error for over an hour now, presumably due to the only child I've allowed coughing and dying. If that is true, why did mutant gen continue beyond route.py ?

Hitting control-C results in:

mutants/PyRoute/DeltaPasses/Canonicalisation.py has invalid syntax:  (unicode error) 'unicodeescape' codec can't decode bytes in position 175-176: malformed \N character escape (<unknown>, line 1507)
^CProcess ForkPoolWorker-5:


Aborted!

[Otto-AA]

Thanks for the details. The string escape sequences are fixed on the master branch, but not yet in a release. (See #396 and related issues). You could try it from the master branch (git clone. Then pip install -e /path/to/mutmut should work I think)

It's been stalled on the Canonicalisation invalid-syntax error for over an hour now, presumably due to the only child I've allowed coughing and dying. If that is true, why did mutant gen continue beyond route.py ?

It's weird behaviour that an error does not stop the mutant generation, likely a side effect of the process pool. If possible we should change that (PRs are welcome if you're interested, though I myself will be gone for some weeks). Not sure why it gets stuck, I'd need to debug that more

[CyberiaResurrection]

Thanks for your help and pointers, @Otto-AA - the git HEAD commit seems to have resolved stalls during mutant generation. Still not testing mutants tho - that will be a different issue.