Don't delete FixtureDef.cached_result, set it to None instead

Previously `cached_result` was either set or deleted. Type annotations
cannot handle this, so use `None` for the non-set state instead.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/_pytest/hookspec.py b/src/_pytest/hookspec.py
index 3cd7f5ffe..62e2155a2 100644
--- a/src/_pytest/hookspec.py
+++ b/src/_pytest/hookspec.py
@@ -423,9 +423,9 @@ def pytest_fixture_setup(fixturedef, request):
 
 
 def pytest_fixture_post_finalizer(fixturedef, request):
-    """ called after fixture teardown, but before the cache is cleared so
-    the fixture result cache ``fixturedef.cached_result`` can
-    still be accessed."""
+    """Called after fixture teardown, but before the cache is cleared, so
+    the fixture result ``fixturedef.cached_result`` is still available (not
+    ``None``)."""
 
 
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