Fix SetupState breakage with upcoming pytest 6.3

pytest 6.3 makes some changes to the SetupState class, adjust to that.

Author: bluetech

CHANGES.rst

@@ -18,6 +18,9 @@ Features
 - Add support for Python 3.9.
   (Thanks to `@digitronik`_ for the PR)
 
+- Add support for pytest 6.3.
+  (Thanks to `@bluetech`_ for the PR)
+
 Other changes
 +++++++++++++
 
@@ -26,6 +29,7 @@ Other changes
 
 .. _@BeyondEvil: https://github.com/BeyondEvil
 .. _@digitronik: https://github.com/digitronik
+.. _@bluetech: https://github.com/bluetech
 
 9.1.1 (2020-09-29)
 ------------------

pytest_rerunfailures.py

@@ -21,6 +21,10 @@
     pytest.__version__
 ) >= pkg_resources.parse_version("5.4")
 
+PYTEST_GTE_63 = pkg_resources.parse_version(
+    pytest.__version__
+) >= pkg_resources.parse_version("6.3.0.dev")
+
 
 def works_with_current_xdist():
     """Returns compatibility with installed pytest-xdist version.
@@ -205,15 +209,17 @@ def _remove_cached_results_from_failed_fixtures(item):
 
 def _remove_failed_setup_state_from_session(item):
     """
-    Note: remove all _prepare_exc attribute from every col in stack of
-          _setupstate and cleaning the stack itself
+    Note: remove all failures from every node in _setupstate stack
+          and clean the stack itself
     """
-    prepare_exc = "_prepare_exc"
-    setup_state = getattr(item.session, "_setupstate")
-    for col in setup_state.stack:
-        if hasattr(col, prepare_exc):
-            delattr(col, prepare_exc)
-    setup_state.stack = list()
+    setup_state = item.session._setupstate
+    if PYTEST_GTE_63:
+        setup_state.stack = {}
+    else:
+        for node in setup_state.stack:
+            if hasattr(node, "_prepare_exc"):
+                del node._prepare_exc
+        setup_state.stack = []
 
 
 def _should_hard_fail_on_error(session_config, report):

tox.ini

@@ -24,6 +24,8 @@ deps =
     pytest54: pytest==5.4.*
     pytest60: pytest==6.0.*
     pytest61: pytest==6.1.*
+    pytest62: pytest==6.2.*
+    pytestmaster: git+https://github.com/pytest-dev/pytest.git@master#egg=pytest
 
 [testenv:linting]
 basepython = python3