Markers are transferred from subclasses to base class methods

[pytestbot]

Originally reported by: BitBucket: foobarbazquux, GitHub: foobarbazquux

---

pytest transfers markers from subclasses to base class methods, which can result in incorrect test selection.

Example code:

#!python
import pytest

class BaseClass():
    def test_foo(self):
        pass

@pytest.mark.test1
class Test1(BaseClass):
    def test_test1(self):
        pass

@pytest.mark.test2
class Test2(BaseClass):
    def test_test2(self):
        pass

Example run showing the test1 marker also being applied to the Test2 base class:

$ py.test -v --collect-only -m test1
================================================================================ test session starts ================================================================================
platform darwin -- Python 2.7.8 -- py-1.4.26 -- pytest-2.6.4 -- /usr/local/opt/python/bin/python2.7
collected 4 items
<Module 'test_example.py'>
  <Class 'Test1'>
    <Instance '()'>
      <Function 'test_foo'>
      <Function 'test_test1'>
  <Class 'Test2'>
    <Instance '()'>
      <Function 'test_foo'>

======================================================================== 1 tests deselected by "-m 'test1'" =========================================================================
=========================================================================== 1 deselected in 0.01 seconds ===========================================================================

More detail from ronny via IRC:

1:52 ronny joesmith: ah, i figured the bug
1:52 ronny hpk: marker transfer to base class test methods fails
1:52 ronny joesmith: we have a mechanism that transfers test markers from the classes to the methods
1:53 ronny joesmith: due to a misstake they trasnfer subclass markers to base class methods
1:53 ronny can you report a issue, i think we can issue a fix this weekend
1:55 ronny hpk: markers on a subclass transfer to a base class method
1:57 ronny https://bitbucket.org/pytest-dev/pytest/src/tip/_pytest/python.py#cl-351 is the "bad" call site
1:58 ronny and https://bitbucket.org/pytest-dev/pytest/src/tip/_pytest/python.py#cl-437 is the implementation
2:01 ronny hpk: its not an easy fix ^^
2:02 ronny hpk: as far as i can tell marker transfer should be part of the marker plugin and the item marker set should be detached from the per object markers
2:03 ronny its a minor restructuring but it has external facing api implications

---

• Bitbucket: https://bitbucket.org/pytest-dev/pytest/issue/725

[nicoddemus]

Duplicate of #568