pytest.RaisesGroup calls the check function with simple exceptions instead of the group #14324

• a detailed description of the bug or problem you are having
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• pytest and operating system versions
• minimal example if possible

The following code:

import pytest

def foo():
    raise ExceptionGroup("Main message", [ValueError("foo")])

def check(exc_group: ExceptionGroup) -> bool:
    print(exc_group.__class__)
    # example check
    return len(exc_group.exceptions) > 1

def test_foo():
    with pytest.RaisesGroup(ValueError, match="Main message", check=check):
        foo()

errors with AttributeError: 'ValueError' object has no attribute 'exceptions' because the check function gets invoked twice, the first time with the exception group for actually performing the check, and the second time with the ValueError raised by the foo function.

As a further proof, the stdout of the run is:

<class 'ExceptionGroup'>
<class 'ValueError'>

This seems wrong, as the docs of RaisesGroup says

check (Callable[[E], bool]) – If specified, a callable that will be called with the group as a parameter after successfully matching the expected exceptions. If it returns True it will be considered a match, if not it will be considered a failed match.

I'm on python 3.12, with just pytest==9.0.2 installed in the environment, but I can reproduce the same issue on 3.14.