[PR #8299/28d026eb backport][3.9] Create marker for internal tests (#…

…8307)

**This is a backport of PR #8299 as merged into master
(28d026e).**

Co-authored-by: Sam Bull <git@sambull.org>

CHANGES/8299.packaging.rst

@@ -0,0 +1,2 @@
+Added an ``internal`` pytest marker for tests which should be skipped
+by packagers (use ``-m 'not internal'`` to disable them) -- by :user:`Dreamsorcerer`.

setup.cfg

@@ -171,3 +171,4 @@ junit_family=xunit2
 xfail_strict = true
 markers =
     dev_mode: mark test to run in dev mode.
+    internal: tests which may cause issues for packagers, but should be run in aiohttp's CI.

tests/test_imports.py

@@ -33,6 +33,7 @@ def test_web___all__(pytester: pytest.Pytester) -> None:
 }
 
 
+@pytest.mark.internal
 @pytest.mark.skipif(
     not sys.platform.startswith("linux") or platform.python_implementation() == "PyPy",
     reason="Timing is more reliable on Linux",