pip 25.1 error when including a group dependency with underscore in name

[user27182]

Description

With pyproject.toml:

[dependency-groups]
foo_bar = []
eggs = [{ include-group = 'foo_bar' }]

Running

pip install . --group eggs

Raises this error:

ERROR: [dependency-groups] resolution failed for 'eggs' from 'pyproject.toml': Dependency group 'foo_bar' not found

Note that installing foo_bar works fine:

 pip install . --group foo_bar

Expected behavior

The install was expected to succeed.

pip version

25.1

Python version

3.12

OS

macOS

How to Reproduce

See above.

Output

See above.

Code of Conduct

• I agree to follow the PSF Code of Conduct.

[ichard26]

cc @sirosen

[sirosen]

I was able to reproduce this purely with dependency-groups, so it's an upstream bug which needs fixing.
Reproducer:

>>> from dependency_groups import DependencyGroupResolver
>>> data = {'dependency-groups': {'foo_bar': [], 'eggs': [{'include-group': 'foo_bar'}]}}
>>> resolver = DependencyGroupResolver(data['dependency-groups'])
>>> resolver.resolve("eggs")
Traceback (most recent call last):  # abbreviated manually

  File ".../dependency_groups/_implementation.py", line 183, in _resolve
    self._resolve(item.include_group, requested_group)
  File ".../dependency_groups/_implementation.py", line 167, in _resolve
    parsed = self._parse_group(group)
             ^^^^^^^^^^^^^^^^^^^^^^^^
  File ".../dependency_groups/_implementation.py", line 131, in _parse_group
    raise LookupError(f"Dependency group '{group}' not found")

I feel like I must have missed testing a case around name normalization, and we're probably using the non-normalized name in a place where the normalized name is needed. Good news is that with such a simple reproducer in hand, it should be fast to test and fix.

[henryiii]

I believe as a workaround, if you have control over the pyproject.toml, you can use the normalized name in the include-group.

[sirosen]

This is fixed now in dependency-groups and I've opened a PR to pull in the update.

As Henry says, if you can edit the file, you can use include-group = 'foo-bar' in the pyproject.toml instead for now.

---

The impact is that any includes which use non-normalized names won't work. Top-level group access with non-normalized names works fine, as the OP noted.

I'm somewhat surprised that this slipped through, but it is brand new code, so not totally shocking.

[user27182]

This is fixed now in dependency-groups and I've opened a PR to pull in the update.

As Henry says, if you can edit the file, you can use include-group = 'foo-bar' in the pyproject.toml instead for now.

Thanks for the quick fix! And thanks for the clarification, it was not obvious to me that the normalized name includes -. I'll use that in the interim.

[pfmoore]

@user27182 can you confirm that the fix has addressed the problem for you? You'll need to install pip from the PR branch (or manually update the vendored copy of dependency-groups in your installation of pip) to test.

[user27182]

I am still getting an install error, unfortunately

pip install --upgrade dependency-groups
pip install . --group eggs 

ERROR: [dependency-groups] resolution failed for 'eggs' from 'pyproject.toml': Dependency group 'foo_bar' not found

pip list

Package           Version
----------------- -------
dependency-groups 1.3.1
packaging         25.0
pip               25.1