1.8.0 missing testing extra, ships unnecessary C source

[musicinmybrain]

Environment details

None of this matters, but:

• OS type and version: Fedora 43
• Python version: Python 3.14.2
• pip version: pip 25.1.1 from /usr/lib/python3.14/site-packages/pip (python 3.14)
• google-crc32c version: 1.8.0

Steps to reproduce

$ git clone https://github.com/googleapis/python-crc32c.git
$ cd python-crc32
$ python3 -m venv _e
$ . _e/bin/activate
$ pip install .[testing]
[…]
WARNING: google-crc32c 1.8.0 does not provide the extra 'testing'
[…]
$ ls -l _e/lib/python3.14/site-packages/google_crc32c/_crc32c.c
-rw-r--r--. 1 ben ben 1428 Dec 16 10:26 _e/lib/python3.14/site-packages/google_crc32c/_crc32c.c

Compare to:

$ pip install google-crc32c[testing]==1.7.1
[… no warnings, correctly install pytest …]
$ ls -l _e/lib/python3.14/site-packages/google_crc32c/_crc32c.c
ls: cannot access '_e/lib/python3.14/site-packages/google_crc32c/_crc32c.c': No such file or directory

Code example

N/A

Stack trace

N/A

Additional information

The problems seems to be that, since googleapis/python-crc32c#319, configuration in setup.cfg is being ignored. Particularly, the issues observed above would not occur if these lines were respected:

https://github.com/googleapis/python-crc32c/blob/9652503fb296eef101d84b9b631f454cc7c1d538/setup.cfg#L43-L48

The obvious solution would be to migrate this configuration to pyproject.toml.

[chalmerlowe]

This issue was moved from the following repo as part of the monorepo migration: googleapis/python-crc32c