RFE: Replace use of pkg_resources with importlib.metadata

[kloczek]

See discussions:
astropy/astropy#11091
pypa/pip#7413

[tkloczko@devel-g2v pytest-7.1.2]$ grep -r pkg_resources
.pre-commit-config.yaml:          - types-pkg_resources
doc/en/announce/release-2.5.0.rst:- refine pytest / pkg_resources interactions: The AssertionRewritingHook
doc/en/announce/release-2.5.0.rst:  PEP302 compliant loader now registers itself with setuptools/pkg_resources
doc/en/announce/release-2.5.0.rst:  properly so that the pkg_resources.resource_stream method works properly.
doc/en/changelog.rst:  It now only calls :func:`pkg_resources.fixup_namespace_packages` if
doc/en/changelog.rst:  ``pkg_resources`` was previously imported, because it is not needed otherwise.
doc/en/changelog.rst:- :issue:`5063`: Switch from ``pkg_resources`` to ``importlib-metadata`` for entrypoint detection for improved performance and import time.
doc/en/changelog.rst:- :issue:`4980`: Namespace packages are handled better with ``monkeypatch.syspath_prepend`` and ``testdir.syspathinsert`` (via ``pkg_resources.fixup_namespace_packages``).
doc/en/changelog.rst:- :issue:`4768`: Avoid pkg_resources import at the top-level.
doc/en/changelog.rst:- :issue:`4315`: Use ``pkg_resources.parse_version`` instead of ``LooseVersion`` in minversion check.
doc/en/changelog.rst:* Fix pkg_resources import error in Jython projects (:issue:`1853`).
doc/en/changelog.rst:- refine pytest / pkg_resources interactions: The AssertionRewritingHook
doc/en/changelog.rst:  :pep:`302` compliant loader now registers itself with setuptools/pkg_resources
doc/en/changelog.rst:  properly so that the pkg_resources.resource_stream method works properly.
doc/en/changelog.rst:  entrypoints via setuptools' pkg_resources.iter_entry_points
doc/en/how-to/monkeypatch.rst:call ``pkg_resources.fixup_namespace_packages`` and :py:func:`importlib.invalidate_caches`.
src/_pytest/monkeypatch.py:        # https://github.com/pypa/setuptools/blob/d8b901bc/docs/pkg_resources.txt#L162-L171
src/_pytest/monkeypatch.py:        # this is only needed when pkg_resources was already loaded by the namespace package
src/_pytest/monkeypatch.py:        if "pkg_resources" in sys.modules:
src/_pytest/monkeypatch.py:            from pkg_resources import fixup_namespace_packages
grep: src/_pytest/__pycache__/monkeypatch.cpython-38.pyc: binary file matches
testing/acceptance_test.py:                "__import__('pkg_resources').declare_namespace(__name__)"
testing/test_assertrewrite.py:        pytest.importorskip("pkg_resources")
testing/test_assertrewrite.py:                import pkg_resources
testing/test_assertrewrite.py:                    res = pkg_resources.resource_string(__name__, 'resource.txt')
testing/test_monkeypatch.py:            "__import__('pkg_resources').declare_namespace(__name__)"

[The-Compiler]

As you can see in the changelog you quoted, that has already happened.

[kloczek]

I see as well lines where that module still is used despite those changelog entries .. 😄

[The-Compiler]

Did you try looking at the code in question?

[kloczek]

No, just checked grep outup as I saw not commented lines with imports I made assumption that still it is something to do .. 🤔

[nicoddemus]

Here's the code in question:

pytest/src/_pytest/monkeypatch.py

Lines 320 to 325 in d949b3f

	# https://github.com/pypa/setuptools/blob/d8b901bc/docs/pkg_resources.txt#L162-L171
	# this is only needed when pkg_resources was already loaded by the namespace package
	if "pkg_resources" in sys.modules:
	from pkg_resources import fixup_namespace_packages
	fixup_namespace_packages(str(path))

pytest itself does not import pkg_resources, but if already imported, then it imports it to call fixup_namespace_packages(), which is the only thing done with pkg_resources. That's what @The-Compiler means.

For everything else pytest already uses importlib.metadata. 👍

[kloczek]

OK, thank you 😄