Add basic implementation of PEP657 style expression markers in tracebacks #13102
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I don't think I'll have time to finish this out fully
Thanks for taking it this far! Whether or not you keep going, this is a neat contribution 😄
There's some interesting problems here like
mypycomplaining because typeshed doesn't have some of the newertraceback.FrameSummaryattrs likecolno.
It looks like typeshed does have them, so I think we're probably seeing mypy pointing out that we need to version-guard those accesses; see comment below.
Additionally, since the python offsets are from the start of the line, we have to know the line before it gets de-dented in
Source.
I think we could fetch it with linecache (as used by the traceback module), and then correct for the different length of leading whitespace? Alternatively we could ast.parse() the Source line, and see if there's an expression which matches the expected start and end colnos for various candidate dedents; it's a heuristic but likely to be unambiguous almost all the time.
| assert reprtb.lines[0] == " return 1 / 0" | ||
| assert reprtb.lines[1] == " ^^^^^" |
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It's not the full fledged python traceback.py implementation where we try to differentiate which parts contain operators.
That would be very nice to have, but I'd be happy to merge something without that and open a follow-up issue: this is already a nice improvement on the status quo!
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Oh yup, you're totally right about them being behind a version check in typeshed, I missed that. Added a version guard and now mypy seems happy with it. Also added version guards for the one unit test I added and changed. |
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Thanks again @ammaraskar!
I think the only thing left is to add yourself to the AUTHORS file, and create changelog/10224.improvement.rst containing something like "Partial support for PEP-657 precise traceback locations in Pytest's alternative traceback formatting."
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Added a changelog and AUTHORS entry. |
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| if frame_summary.end_lineno is None: | ||
| return None |
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Hmm, looks like we need tests covering this branch - though I'm not sure there's a nice way to get that, so maybe a # pragma: no cover instead? Hmm.
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Yeah, it would be tough to disable the column information to test this branch. Added a no cover.
ammaraskar
changed the title
Hey folks this is just a proof of concept for #10224 to serve as a reference for if any contributor wants to give this a full shot.
This adds a very basic implementation of the PEP657 style expression highlighting in the short and long traceback modes. It's not the full fledged python
traceback.pyimplementation where we try to differentiate which parts contain operators.I don't think I'll have time to finish this out fully, there's some interesting problems here like
mypycomplaining because typeshed doesn't have some of the newertracebackFrameSummaryattrs likecolno. Additionally, since the python offsets are from the start of the line, we have to know the line before it gets de-dented inSource.Example of what it looks like:
and with tb short: