Fix test_exceptions_dont_leak in Python 3.12 (#535)

Fixes #532

Author: nicoddemus

CHANGELOG.rst

@@ -1,3 +1,10 @@
+UNRELEASED
+----------
+
+- Fixed exception handling so they are properly cleared in Python 3.12, due to the new `sys.last_exc <https://docs.python.org/3/library/sys.html#sys.last_exc>`__ attribute (`#532`_).
+
+..  _#532: https://github.com/pytest-dev/pytest-qt/issues/532
+
 4.3.1 (2023-12-22)
 ------------------
 

src/pytestqt/exceptions.py

@@ -65,6 +65,8 @@ def fail_if_exceptions_occurred(self, when):
             prefix = "%s ERROR: " % when
             msg = prefix + format_captured_exceptions(exceptions)
             del exceptions[:]  # Don't keep exceptions alive longer.
+            if hasattr(sys, "last_exc"):
+                sys.last_exc = None
             pytest.fail(msg, pytrace=False)
 
 

tests/test_exceptions.py

@@ -365,9 +365,6 @@ def event(self, ev):
 
 
 @exception_capture_pyside6
-@pytest.mark.skipif(
-    sys.version_info[:2] == (3, 12), reason="#532 requires investigation"
-)
 def test_exceptions_dont_leak(testdir):
     """
     Ensure exceptions are cleared when an exception occurs and don't leak (#187).