Fix missing marks when inheritance from multiple classes

Closes pytest-dev#7792

AUTHORS

@@ -104,6 +104,7 @@ Edison Gustavo Muenz
 Edoardo Batini
 Edson Tadeu M. Manoel
 Eduardo Schettino
+Efraimov Oren
 Eli Boyarski
 Elizaveta Shashkova
 Éloi Rivard

doc/en/changelog.rst

@@ -31,6 +31,11 @@ with advance notice in the **Deprecations** section of releases.
 pytest 6.2.5 (2021-08-29)
 =========================
 
+Bug Fixes
+---------
+
+- `#7792 <https://github.com/pytest-dev/pytest/issues/7792>`_: Fixing missing marks when inheritance from multiple classes.
+
 
 Trivial/Internal Changes
 ------------------------

src/_pytest/mark/structures.py

@@ -4,6 +4,7 @@
 from typing import Any
 from typing import Callable
 from typing import Collection
+from typing import Dict
 from typing import Iterable
 from typing import Iterator
 from typing import List
@@ -368,6 +369,24 @@ def get_unpacked_marks(obj) -> List[Mark]:
     return normalize_mark_list(mark_list)
 
 
+MARKERS_BY_CLASS_NAME: Dict[str, List[Mark]] = {}
+
+
+def get_all_mro_marks(cls, module_name):
+    all_markers = getattr(cls, "pytestmark", [])
+    if cls is None:
+        return all_markers
+    if not isinstance(all_markers, list):
+        all_markers = [all_markers]
+    for parent_obj in cls.__mro__[::-1]:
+        full_class_name = f"{module_name}_{parent_obj.__name__}"
+        if not MARKERS_BY_CLASS_NAME.get(full_class_name):
+            MARKERS_BY_CLASS_NAME[full_class_name] = get_unpacked_marks(parent_obj)
+        all_markers.extend(MARKERS_BY_CLASS_NAME[full_class_name])
+    setattr(cls, "pytestmark", list({str(mark): mark for mark in all_markers}.values()))
+    return cls.pytestmark
+
+
 def normalize_mark_list(mark_list: Iterable[Union[Mark, MarkDecorator]]) -> List[Mark]:
     """
     Normalize an iterable of Mark or MarkDecorator objects into a list of marks

src/_pytest/python.py

@@ -60,6 +60,7 @@
 from _pytest.main import Session
 from _pytest.mark import MARK_GEN
 from _pytest.mark import ParameterSet
+from _pytest.mark.structures import get_all_mro_marks
 from _pytest.mark.structures import get_unpacked_marks
 from _pytest.mark.structures import Mark
 from _pytest.mark.structures import MarkDecorator
@@ -1586,6 +1587,7 @@ def __init__(
         # to a readonly property that returns FunctionDefinition.name.
 
         self.keywords.update(self.obj.__dict__)
+        self.own_markers.extend(get_all_mro_marks(self.cls, self.module.__name__))
         self.own_markers.extend(get_unpacked_marks(self.obj))
         if callspec:
             self.callspec = callspec

testing/test_mark.py

@@ -1127,3 +1127,35 @@ def test_foo():
     result = pytester.runpytest(foo, "-m", expr)
     result.stderr.fnmatch_lines([expected])
     assert result.ret == ExitCode.USAGE_ERROR
+
+
+@pytest.mark.parametrize(
+    "markers",
+    (
+        "mark1",
+        "mark1 and mark2",
+        "mark1 and mark2 and mark3",
+        "mark1 and mark2 and mark3 and mark4",
+    ),
+)
+def test_markers_from_multiple_inheritances(pytester: Pytester, markers) -> None:
+    py_file = pytester.makepyfile(
+        """
+        import pytest
+        @pytest.mark.mark1
+        class Base1:
+            pass
+
+        @pytest.mark.mark2
+        class Base2:
+            pass
+
+        @pytest.mark.mark3
+        class TestMultipleInheritances(Base1, Base2):
+            @pytest.mark.mark4
+            def test_multiple_inheritances(self):
+                pass
+        """
+    )
+    result = pytester.inline_run(py_file, "-m", markers)
+    result.assertoutcome(passed=1)