issues: 1772218488

What happened?

Looks like pytest is failing on scanning units.

What did you expect to happen?

pytest should not fail.

Minimal Complete Verifiable Example

I'm packaging your module as an rpm package so I'm using the typical PEP517 based build, install and test cycle used on building packages from non-root account. - python3 -sBm build -w --no-isolation - because I'm calling build with --no-isolation I'm using during all processes only locally installed modules - install .whl file in </install/prefix> using 'installermodule - run pytest with $PYTHONPATH pointing to sitearch and sitelib inside </install/prefix> - build is performed in env which is *cut off from access to the public network* (pytest is executed with-m "not network"`)

MVCE confirmation

• [X] Minimal example — the example is as focused as reasonably possible to demonstrate the underlying issue in xarray.
• [X] Complete example — the example is self-contained, including all data and the text of any traceback.
• [ ] Verifiable example — the example copy & pastes into an IPython prompt or Binder notebook, returning the result.
• [X] New issue — a search of GitHub Issues suggests this is not a duplicate.

Relevant log output

Here is pytest output:

```console + PYTHONPATH=/home/tkloczko/rpmbuild/BUILDROOT/python-xarray-2023.05.0-2.fc35.x86_64/usr/lib64/python3.8/site-packages:/home/tkloczko/rpmbuild/BUILDROOT/python-xarray-2023.05.0-2.fc35.x86_64/usr/lib/python3.8/site-packages + /usr/bin/pytest -ra -m 'not network' --pyargs xarray ImportError while loading conftest '/home/tkloczko/rpmbuild/BUILD/xarray-2023.05.0/xarray/tests/conftest.py'. xarray/__init__.py:1: in <module> from xarray import testing, tutorial xarray/testing.py:10: in <module> from xarray.core import duck_array_ops, formatting, utils xarray/core/duck_array_ops.py:36: in <module> from xarray.core import dask_array_ops, dtypes, nputils xarray/core/dask_array_ops.py:3: in <module> from xarray.core import dtypes, nputils xarray/core/dtypes.py:7: in <module> from xarray.core import utils xarray/core/utils.py:443: in <module> class Frozen(Mapping[K, V]): E TypeError: 'ABCMeta' object is not subscriptable ```

Anything else we need to know?

No response

Environment

Here is list of installed modules in build env

```console Package Version ----------------------------- ------- alabaster 0.7.13 asttokens 2.2.1 attrs 23.1.0 autocommand 2.2.1 Babel 2.12.1 backcall 0.2.0 build 0.10.0 cffi 1.15.1 charset-normalizer 3.1.0 coverage 7.2.7 cryptography 40.0.2 decorator 5.1.1 distro 1.8.0 docutils 0.19 exceptiongroup 1.1.1 executing 1.2.0 filelock 3.12.2 flake8 5.0.4 gpg 1.20.0 idna 3.4 imagesize 1.4.1 importlib-metadata 6.6.0 importlib-resources 5.12.0 iniconfig 2.0.0 installer 0.7.0 ipython 8.12.0 jaraco.classes 3.2.3 jaraco.context 4.3.0 jaraco.packaging 9.2.0 jaraco.tidelift 1.5.1 jedi 0.18.2 jeepney 0.8.0 Jinja2 3.1.2 jsonref 1.1.0 jsonschema 4.17.3 keyring 23.13.1 libcomps 0.1.19 MarkupSafe 2.1.2 matplotlib-inline 0.1.6 mccabe 0.7.0 more-itertools 9.1.0 msgpack 1.0.5 mypy 1.3.0 mypy-extensions 1.0.0 packaging 23.1 parso 0.8.3 pexpect 4.8.0 pickleshare 0.7.5 pkgutil_resolve_name 1.3.10 pluggy 1.0.0 ply 3.11 prompt-toolkit 3.0.38 ptyprocess 0.7.0 pure-eval 0.2.2 pycodestyle 2.9.1 pycparser 2.21 pyflakes 2.5.0 Pygments 2.15.1 pyproject_hooks 1.0.0 pyrsistent 0.19.3 pytest 7.3.1 pytest-cov 4.0.0 pytest-flake8 1.1.1 pytest-mypy 0.10.3 python-dateutil 2.8.2 pytz 2023.2 PyYAML 6.0 requests 2.31.0 requests-toolbelt 1.0.0 rst.linker 2.4.0 SecretStorage 3.3.3 setuptools 67.7.2 setuptools-scm 7.1.0 simplejson 3.19.1 six 1.16.0 snowballstemmer 2.2.0 Sphinx 6.2.1 sphinx-rtd-theme 1.2.1 sphinxcontrib-applehelp 1.0.4 sphinxcontrib-devhelp 1.0.2 sphinxcontrib-htmlhelp 2.0.0 sphinxcontrib-jquery 4.1 sphinxcontrib-jsmath 1.0.1 sphinxcontrib-qthelp 1.0.3 sphinxcontrib-serializinghtml 1.1.5 stack-data 0.6.2 swagger-spec-validator 3.0.3 tomli 2.0.1 traitlets 5.9.0 typing_extensions 4.5.0 urllib3 1.26.15 wcwidth 0.2.6 wheel 0.40.0 zipp 3.15.0 ```