Too tight a type constraint on ExceptionInfo.errisinstance

[gmc444-b]

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With pytest 8.2.2 the declaration of ExceptionInfo.errisinstance was

     def errisinstance(
        self, exc: Union[Type[BaseException], Tuple[Type[BaseException], ...]]
    ) -> bool:

With 8.3.1, this has changed, first by introducing a type spec, and then using that typespec for the function signature

EXCEPTION_OR_MORE = Union[Type[Exception], Tuple[Type[Exception], ...]]
    ...
    def errisinstance(self, exc: EXCEPTION_OR_MORE) -> bool:

Version 8.2.2 would pass a mypy check with the following reproducer. Version 8.3.1 fails (I didn't test with 8.3.0 but I'd expect that to also fail). I tested this with mypy versions 1.10.1 and 1.11.0, but I'd expect it to fail for pretty much any supported version of mypy.

import sys
import pytest


def test_iserrinstance() -> None:
    def bad() -> None:
        sys.exit()

    with pytest.raises(BaseException) as exc:
        bad()
    assert exc.errisinstance(SystemExit)

# Error output:
python3.10 -m mypy reproducer.py
reproducer.py:12: error: "ExceptionInfo[BaseException]" has no attribute "iserrinstance"; maybe "errisinstance"?  [attr-defined]
Found 1 error in 1 file (checked 1 source file)

The change was made in this commit but I'm not finding an explanation there as to why the type was changed from BaseException to Exception.

To me, it looks like the best fix is to change EXCEPTION_OR_MORE to

EXCEPTION_OR_MORE = Union[Type[BaseException], Tuple[Type[BaseException], ...]]

restoring backward compatibility.

[RonnyPfannschmidt]

This is a oversight on my part,it needs a fix

[nicoddemus]

Just to clarify @RonnyPfannschmidt is that something you will tackle, or PRs are welcome?

[RonnyPfannschmidt]

Prs Welcome, I'm not at capacity ATM