ValueError: PurePosixPath('.') has an empty name

[chingc]

Hi, I'm running Python 3.11.2 and pytest 7.2.1 on macOS (Ventura 13.1) with Apple Silicon and I'm running into the following error:

ValueError: PurePosixPath('.') has an empty name

I was able to trace the error to this change: f92c4a7

The error occurs when calling with_suffix when parts is an empty list. Here's an example:

Python 3.11.2 (main, Feb 16 2023, 02:55:59) [Clang 14.0.0 (clang-1400.0.29.202)] on darwin
Type "help", "copyright", "credits" or "license" for more information.

>>> import os
>>> from pathlib import PurePath
>>> parts = ['']

# result is the same when not dealing with the suffix
>>> PurePath(os.path.sep.join(parts)) == PurePath(*parts)
True

# old code: empty parts with suffix returns the suffix
>>> PurePath(os.path.sep.join(parts) + ".py")
PurePosixPath('.py')

# new code: empty parts with suffix throws an exception
>>> PurePath(*parts).with_suffix(".py")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/opt/homebrew/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/pathlib.py", line 694, in with_suffix
    raise ValueError("%r has an empty name" % (self,))
ValueError: PurePosixPath('.') has an empty name

I haven't been able to figure out why parts is ever empty, but with what I know I was able to temporarily workaround this problem by downgrading to pytest 7.1.2.

[theirix]

Could you please describe a project layout or example where you have got this error? Could not reproduce it.

[github-actions]

This issue is stale because it has been open for 14 days with no activity.

[github-actions]

This issue was closed because it has been inactive for 7 days since being marked as stale.

[jgarvin]

@theirix can confirm this still exists. I use this code to import a module at runtime:

def _import_from_filename(file_path: Path) -> ModuleType:
    """Try to import with exactly the module path we would have gotten
    had we imported manually."""
    relative_path = file_path.strict_relative_to(SOURCE_ROOT.get())
    module_name = str(relative_path.with_suffix('')).replace('/', '.')

    if module_name in sys.modules:
        log.info(f"Already imported {module_name}")
        return sys.modules[module_name]  # already imported

    log.info(f"Importing module={file_path}")
    spec = importlib.util.spec_from_file_location(module_name, file_path)
    assert spec
    assert spec.loader
    module = importlib.util.module_from_spec(spec)
    sys.modules[module_name] = module
    spec.loader.exec_module(module)
    return module

that module contains a relative import:

from .rule_a import a_rule

which triggers the error. the import has to be relative in order to trigger

[RonnyPfannschmidt]

#11426 should be there fix

[jgarvin]

@RonnyPfannschmidt I did a fresh python3.11 -m pip install 'pytest @ git+https://github.com/pytest-dev/pytest.git' but still get the error

[The-Compiler]

Can you please share the full output and ideally a reproducer we can run?

[nicoddemus]

Wait, what does the code posted in #10764 (comment) has to do with pytest? IIUC, that's custom code which uses importlib, but has no relation to pytest.