Errors when tox is setting up the test environment

[abravalheri]

In the series of PRs that were targeting improving PKG-INFO all the tests seemed to have been running fine.
This is evidenced by the all green CI in #4029 (last change) before it was merged into main.

However, it started failing in the moment I did the merge. I am not sure what is happening, and I am trying to investigate why.

tox
  shell: /usr/bin/bash -e {0}
  env:
    FORCE_COLOR: 1
    MYPY_FORCE_COLOR: -42
    PY_COLORS: 1
    TOX_TESTENV_PASSENV: FORCE_COLOR MYPY_FORCE_COLOR NO_COLOR PY_COLORS PYTEST_THEME PYTEST_THEME_MODE
    PIP_DISABLE_PIP_VERSION_CHECK: true
    PIP_NO_PYTHON_VERSION_WARNING: true
    PIP_NO_WARN_SCRIPT_LOCATION: true
    TOX_PARALLEL_NO_SPINNER: 1
    TOXENV: docs
docs: install_deps> python -I -m pip install 'importlib_resources<6'
.pkg: _optional_hooks> python /home/runner/.local/lib/python[3](https://github.com/pypa/setuptools/actions/runs/6015752069/job/16318875362#step:5:3).10/site-packages/pyproject_api/_backend.py True setuptools.build_meta
.pkg: get_requires_for_build_editable> python /home/runner/.local/lib/python3.10/site-packages/pyproject_api/_backend.py True setuptools.build_meta
.pkg: install_requires_for_build_editable> python -I -m pip install wheel
.pkg: freeze> python -m pip freeze --all
.pkg: pip==23.2.1,setuptools==68.0.0,wheel==0.[4](https://github.com/pypa/setuptools/actions/runs/6015752069/job/16318875362#step:5:4)1.1
docs: internal error
Traceback (most recent call last):
  File "/home/runner/.local/lib/python3.10/site-packages/tox/session/cmd/run/single.py", line 46, in _evaluate
    tox_env.setup()
  File "/home/runner/.local/lib/python3.10/site-packages/tox/tox_env/api.py", line 248, in setup
    self._setup_with_env()
  File "/home/runner/.local/lib/python3.10/site-packages/tox/tox_env/runner.py", line 14[5](https://github.com/pypa/setuptools/actions/runs/6015752069/job/16318875362#step:5:5), in _setup_with_env
    self._setup_pkg()
  File "/home/runner/.local/lib/python3.10/site-packages/tox/tox_env/runner.py", line 1[6](https://github.com/pypa/setuptools/actions/runs/6015752069/job/16318875362#step:5:6)8, in _setup_pkg
    self._packages = self._build_packages()
  File "/home/runner/.local/lib/python3.10/site-packages/tox/tox_env/python/runner.py", line 119, in _build_packages
    packages = package_env.perform_packaging(self.conf)
  File "/home/runner/.local/lib/python3.10/site-packages/tox/tox_env/package.py", line 45, in _func
    return meth(*args, **kwargs)
  File "/home/runner/.local/lib/python3.10/site-packages/tox/tox_env/python/virtual_env/package/pyproject.py", line 189, in perform_packaging
    deps = self._load_deps(for_env)
  File "/home/runner/.local/lib/python3.10/site-packages/tox/tox_env/package.py", line 45, in _func
    return meth(*args, **kwargs)
  File "/home/runner/.local/lib/python3.10/site-packages/tox/tox_env/python/virtual_env/package/pyproject.py", line 248, in _load_deps
    deps = self._load_deps_from_built_metadata(for_env)
  File "/home/runner/.local/lib/python3.10/site-packages/tox/tox_env/package.py", line 45, in _func
    return meth(*args, **kwargs)
  File "/home/runner/.local/lib/python3.10/site-packages/tox/tox_env/python/virtual_env/package/pyproject.py", line 292, in _load_deps_from_built_metadata
    reqs = self.get_package_dependencies(for_env)
  File "/home/runner/.local/lib/python3.10/site-packages/tox/tox_env/package.py", line 45, in _func
    return meth(*args, **kwargs)
  File "/home/runner/.local/lib/python3.10/site-packages/tox/tox_env/python/virtual_env/package/pyproject.py", line 300, in get_package_dependencies
    self._ensure_meta_present(for_env)
  File "/home/runner/.local/lib/python3.10/site-packages/tox/tox_env/package.py", line 45, in _func
    return meth(*args, **kwargs)
  File "/home/runner/.local/lib/python3.10/site-packages/tox/tox_env/python/virtual_env/package/pyproject.py", line 321, in _ensure_meta_present
    dist_info = hook(self.meta_folder, self._wheel_config_settings).metadata
AttributeError: 'NoneType' object has no attribute 'metadata'
.pkg: _exit> python /home/runner/.local/lib/python3.10/site-packages/pyproject_api/_backend.py True setuptools.build_meta
  docs: FAIL code 2 (3.62 seconds)
  evaluation failed :( (3.[7](https://github.com/pypa/setuptools/actions/runs/6015752069/job/16318875362#step:5:7)3 seconds)

It seems that tox finds an error when calling prepare_metadata_for_build_editable however I am not sure it even gets to run this function from build_meta...

As a last resort we can revert the merge and return the repository to its last safe version.

[abravalheri]

May be related to the latest 2 releases of tox-dev/pyproject-api (1.6.0 and 1.6.1) in the latest couple of hours, but I am not sure... Still have to investigate more.

[abravalheri]

Might be fixed by tox==4.11.0. I will run the tests again manually to verify.

[Nusnus]

I am experiencing the same issue randomly too regarding unrelated code changes (celery/celery#8463).
I am capped at tox <4.9 and everything was working fine yesterday.

[abravalheri]

@Nusnus, you can also update to tox==4.11.0.

I will close the issue now since things seem to be fine and there is nothing to do in setuptools.

[Nusnus]

@Nusnus, you can also update to tox==4.11.0.

I will close the issue now since things seem to be fine and there is nothing to do in setuptools.

It worked!
Thanks 👍