Apply suggestions from code review

Co-authored-by: Ran Benita <ran@unusedvar.com>

Author: RonnyPfannschmidt

changelog/7792.bugfix.rst

@@ -1 +1,5 @@
-Consider the full mro when getting marks from classes.
+Marks are now inherited according to the full MRO in test classes. Previously, if a test class inherited from two or more classes, only marks from the first super-class would apply.
+
+When inheriting marks from super-classes, marks from the sub-classes are now ordered before marks from the super-classes, in MRO order. Previously it was the reverse.
+
+When inheriting marks from super-classes, the `pytestmark` attribute of the sub-class now only contains the marks directly applied to it. Previously, it also contained marks from its super-classes. Please note that this attribute should not normally be accessed directly; use :func:`pytest.Node.iter_markers` instead.

src/_pytest/mark/structures.py

@@ -357,9 +357,15 @@ def __call__(self, *args: object, **kwargs: object):
 
 def get_unpacked_marks(
     obj: Union[object, type],
+    *,
     consider_mro: bool = True,
 ) -> List[Mark]:
-    """Obtain the unpacked marks that are stored on an object."""
+    """Obtain the unpacked marks that are stored on an object.
+    
+    If obj is a class and consider_mro is true, return marks applied to
+    this class and all of its super-classes in MRO order. If consider_mro
+    is false, only return marks applied directly to this class.
+    """
     if isinstance(obj, type):
         if not consider_mro:
             mark_lists = [obj.__dict__.get("pytestmark", [])]

testing/test_mark.py

@@ -1111,7 +1111,7 @@ def test_foo():
     assert result.ret == ExitCode.USAGE_ERROR
 
 
-def test_mark_mro():
+def test_mark_mro() -> None:
     xfail = pytest.mark.xfail
 
     @xfail("a")