From 567739483c23f0a9146f731427299143b1453e36 Mon Sep 17 00:00:00 2001
From: Yaniv Michael Kaul <yaniv.kaul@scylladb.com>
Date: Thu, 26 Mar 2026 12:06:14 +0200
Subject: [PATCH] fix: make HashableMock thread-safe by restoring __hash__
 after MagicMixin
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NonCallableMagicMock.__init__ (via MagicMixin) replaces __hash__ on the
type with a MagicMock object. That MagicMock is not thread-safe, so
concurrent hash() calls — e.g. `connection in self._trash` in pool.py
return_connection — can raise `TypeError: __hash__ method should return
an integer` under concurrent access on Windows.

The previous __hash__ override was dead code: MagicMixin.__init__ always
replaced it with a MagicMock before any test could call it.

Fix by restoring a plain function as the class-level __hash__ after
super().__init__ runs, so hash() always resolves to a real function
instead of a thread-unsafe MagicMock callable.

Fixes flaky test_successful_wait_for_connection on Windows CI.
---
 tests/unit/util.py | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/tests/unit/util.py b/tests/unit/util.py
index 042f07fb99..8aa5b96f93 100644
--- a/tests/unit/util.py
+++ b/tests/unit/util.py
@@ -32,6 +32,24 @@ def _check_order_consistency(smaller, bigger, equal=False):
 
 
 class HashableMock(NonCallableMagicMock):
+    """A Mock subclass that is safely hashable and usable in sets/dicts.
 
-    def __hash__(self):
-        return id(self)
\ No newline at end of file
+    NonCallableMagicMock's __init__ (via MagicMixin) replaces __hash__
+    on the *type* with a MagicMock object.  That MagicMock is not
+    thread-safe, so concurrent hash() calls on the same instance —
+    e.g. ``connection in self._trash`` in pool.py — can raise
+    ``TypeError: __hash__ method should return an integer`` on Windows.
+
+    We fix this by restoring a plain function as the class-level
+    __hash__ after super().__init__ runs, so hash() always resolves to
+    a real function (id-based) instead of a MagicMock callable.
+    """
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        # Restore a real __hash__ after MagicMixin overwrites it.
+        type(self).__hash__ = HashableMock._id_hash
+
+    @staticmethod
+    def _id_hash(self):
+        return id(self)