test: ignore the warnings about becoming a fixture via config.

changelog/12989.improvement.rst

@@ -1 +1,8 @@
-Issues a warning when a function is not collected as a test case just because it uses :py:func:`@pytest.fixture`
+Issues a warning when a function is not collected as a test case just because it uses :py:func:`@pytest.fixture`.
+This helps beginners distinguish fixtures from tests; experienced users can ignore the warning via config.
+
+.. code-block:: ini
+
+    [pytest]
+    filterwarnings =
+        ignore:.*becomes a fixture.*:pytest.PytestCollectionWarning

pyproject.toml

@@ -403,6 +403,7 @@ filterwarnings = [
     "ignore:VendorImporter\\.find_spec\\(\\) not found; falling back to find_module\\(\\):ImportWarning",
     # https://github.com/pytest-dev/execnet/pull/127
     "ignore:isSet\\(\\) is deprecated, use is_set\\(\\) instead:DeprecationWarning",
+    "ignore:.*becomes a fixture.*:pytest.PytestCollectionWarning",
 ]
 pytester_example_dir = "testing/example_scripts"
 markers = [