From c0bd9b1b36ff81ce3e238ace8696525158aceb1d Mon Sep 17 00:00:00 2001
From: Ronan Merrick <ronan.merrick@mongodb.com>
Date: Sat, 27 Jun 2026 14:50:09 +0100
Subject: [PATCH 1/8] PYTHON-5904

---
 pymongo/asynchronous/pool.py | 3 ++-
 pymongo/synchronous/pool.py  | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/pymongo/asynchronous/pool.py b/pymongo/asynchronous/pool.py
index 60acb93fcd..8c8d7ca267 100644
--- a/pymongo/asynchronous/pool.py
+++ b/pymongo/asynchronous/pool.py
@@ -294,7 +294,8 @@ async def _hello(
             hello.logical_session_timeout_minutes is not None and hello.is_readable
         )
         self.logical_session_timeout_minutes: Optional[int] = hello.logical_session_timeout_minutes
-        self.hello_ok = hello.hello_ok
+        # PYTHON-5904
+        self.hello_ok = self.hello_ok or hello.hello_ok
         self.is_repl = hello.server_type in (
             SERVER_TYPE.RSPrimary,
             SERVER_TYPE.RSSecondary,
diff --git a/pymongo/synchronous/pool.py b/pymongo/synchronous/pool.py
index b3929b674a..48b0010f5c 100644
--- a/pymongo/synchronous/pool.py
+++ b/pymongo/synchronous/pool.py
@@ -294,7 +294,8 @@ def _hello(
             hello.logical_session_timeout_minutes is not None and hello.is_readable
         )
         self.logical_session_timeout_minutes: Optional[int] = hello.logical_session_timeout_minutes
-        self.hello_ok = hello.hello_ok
+        # PYTHON-5904
+        self.hello_ok = self.hello_ok or hello.hello_ok
         self.is_repl = hello.server_type in (
             SERVER_TYPE.RSPrimary,
             SERVER_TYPE.RSSecondary,

From 2293e362ef5f3d7ceefa425be5e0c1fe0a8be639 Mon Sep 17 00:00:00 2001
From: Ronan Merrick <ronan.merrick@mongodb.com>
Date: Tue, 30 Jun 2026 10:38:52 +0100
Subject: [PATCH 2/8] added regression tests for PYTHON-5904

---
 test/asynchronous/test_hello_latched.py | 67 ++++++++++++++++++++++
 test/test_hello_latched.py              | 74 +++++++++++++++++++++++++
 2 files changed, 141 insertions(+)
 create mode 100644 test/asynchronous/test_hello_latched.py
 create mode 100644 test/test_hello_latched.py

diff --git a/test/asynchronous/test_hello_latched.py b/test/asynchronous/test_hello_latched.py
new file mode 100644
index 0000000000..127d093937
--- /dev/null
+++ b/test/asynchronous/test_hello_latched.py
@@ -0,0 +1,67 @@
+import unittest
+from unittest.mock import AsyncMock 
+from types import SimpleNamespace
+from pymongo.asynchronous.pool import AsyncConnection 
+
+class TestHelloLatched(unittest.IsolatedAsyncioTestCase):
+
+    def setUp(self):
+        self._sent = []
+
+    def create_connection(self) -> AsyncConnection:
+        """Returns a minimal connection object for _hello"""
+        conn = object.__new__(AsyncConnection)
+        conn.hello_ok = False
+        conn.performed_handshake = True
+        conn.opts = SimpleNamespace(
+            server_api = None,
+            load_balanced = False,
+            _credentials = None
+        )
+
+        return conn
+
+    async def mock_conn_command(self, db, cmd, **kwargs):
+        """Returns mocked hello and ismaster results for conn.command"""
+        self._sent.append(cmd.copy())
+        if cmd.get("ismaster") == 1:
+            return {"ok":1, "helloOk": True, "ismaster": True, "maxWireVersion": 25}
+        return {"ok":1, "isWritablePrimary": True, "maxWireVersion": 25}
+
+
+    async def test_hello_is_latched(self):
+        """
+        Regression Test for PYTHON-5904
+        Tests for connection hello_ok persistence when connection
+        Switches from ismaster to hello
+        """
+        conn = self.create_connection()
+        conn.command = AsyncMock(side_effect=self.mock_conn_command)
+
+        # First hello
+        await conn._hello(None, None)
+        # Verify hello_ok is True
+        self.assertTrue(conn.hello_ok)
+        # Verify command sent is ismaster
+        self.assertEqual(self._sent[0].get("ismaster"), 1)
+        self.assertEqual(self._sent[0].get("helloOk"), True)
+
+        # Second hello
+        await conn._hello(None, None)
+        # Verify hello_ok has not changed
+        self.assertTrue(conn.hello_ok)
+        # Verify command sent is hello
+        self.assertEqual(self._sent[1].get("hello"), 1)
+        self.assertIsNone(self._sent[1].get("ismaster", None))
+
+        # Third hello
+        await conn._hello(None, None)
+        # Verify connection continues to use hello
+        self.assertEqual(self._sent[2].get("hello"), 1)
+        self.assertIsNone(self._sent[1].get("ismaster", None))
+
+
+if __name__ == "__main__":
+    unittest.main()
+
+
diff --git a/test/test_hello_latched.py b/test/test_hello_latched.py
new file mode 100644
index 0000000000..303686fe17
--- /dev/null
+++ b/test/test_hello_latched.py
@@ -0,0 +1,74 @@
+import unittest
+from unittest.mock import Mock 
+from types import SimpleNamespace
+from pymongo.synchronous.pool import Connection 
+
+
+class TestHelloLatched(unittest.TestCase):
+    """
+    Test to Ensure that hello_ok remains latched
+    when the RTT thread switches to hello
+    """
+
+    def setUp(self):
+        self._sent = []
+
+    def create_connection(self) -> Connection:
+        """Returns a minimal connection object"""
+        conn = object.__new__(Connection)
+        conn.hello_ok = False
+        # Isolate this test to post-handshake hello_ok persistence
+        conn.performed_handshake = True
+        conn.opts = SimpleNamespace(
+            server_api = None,
+            load_balanced = False,
+            _credentials = None
+        )
+
+        return conn
+
+    def mock_connection_command(self, db, cmd, **kwargs):
+        """Returns mocked hello and ismaster results for conn.command"""
+        self._sent.append(cmd.copy())
+        if cmd.get("ismaster") == 1:
+            return {"ok":1, "helloOk": True, "ismaster": True, "maxWireVersion": 25}
+        return {"ok":1, "isWritablePrimary": True, "maxWireVersion": 25}
+
+
+    def test_hello_is_latched(self):
+        """
+        Regression Test for PYTHON-5904
+        Tests for connection hello_ok persistence when connection
+        Switches from ismaster to hello
+        """
+
+        conn = self.create_connection()
+        conn.command = Mock(side_effect=self.mock_connection_command)
+
+        # First hello
+        conn._hello(None, None)
+        # Verify hello_ok is True
+        self.assertTrue(conn.hello_ok)
+        # Verify command sent is ismaster
+        self.assertEqual(self._sent[0].get("ismaster"), 1)
+        self.assertEqual(self._sent[0].get("helloOk"), True)
+
+        # Second hello
+        conn._hello(None, None)
+        # Verify hello_ok has not changed
+        self.assertTrue(conn.hello_ok)
+        # Verify command sent is hello
+        self.assertEqual(self._sent[1].get("hello"), 1)
+        self.assertIsNone(self._sent[1].get("ismaster", None))
+
+        # Third hello
+        conn._hello(None, None)
+        # Verify connection continues to use hello
+        self.assertEqual(self._sent[2].get("hello"), 1)
+        self.assertIsNone(self._sent[1].get("ismaster", None))
+
+
+if __name__ == "__main__":
+    unittest.main()
+
+

From b7961a7da98e8b1527d6c873c5cbab21f95006ce Mon Sep 17 00:00:00 2001
From: Ronan Merrick <ronan.merrick@mongodb.com>
Date: Tue, 30 Jun 2026 16:46:02 +0100
Subject: [PATCH 3/8] PR changes

---
 pymongo/synchronous/pool.py             |  3 +-
 test/asynchronous/test_hello_latched.py | 18 +++++-
 test/test_hello_latched.py              | 74 -------------------------
 3 files changed, 18 insertions(+), 77 deletions(-)
 delete mode 100644 test/test_hello_latched.py

diff --git a/pymongo/synchronous/pool.py b/pymongo/synchronous/pool.py
index 48b0010f5c..b3929b674a 100644
--- a/pymongo/synchronous/pool.py
+++ b/pymongo/synchronous/pool.py
@@ -294,8 +294,7 @@ def _hello(
             hello.logical_session_timeout_minutes is not None and hello.is_readable
         )
         self.logical_session_timeout_minutes: Optional[int] = hello.logical_session_timeout_minutes
-        # PYTHON-5904
-        self.hello_ok = self.hello_ok or hello.hello_ok
+        self.hello_ok = hello.hello_ok
         self.is_repl = hello.server_type in (
             SERVER_TYPE.RSPrimary,
             SERVER_TYPE.RSSecondary,
diff --git a/test/asynchronous/test_hello_latched.py b/test/asynchronous/test_hello_latched.py
index 127d093937..e173301c98 100644
--- a/test/asynchronous/test_hello_latched.py
+++ b/test/asynchronous/test_hello_latched.py
@@ -1,3 +1,19 @@
+# Copyright 2022-present MongoDB, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Test that connection continues to use hello after ismaster returns hello_ok"""
+
 import unittest
 from unittest.mock import AsyncMock 
 from types import SimpleNamespace
@@ -58,7 +74,7 @@ async def test_hello_is_latched(self):
         await conn._hello(None, None)
         # Verify connection continues to use hello
         self.assertEqual(self._sent[2].get("hello"), 1)
-        self.assertIsNone(self._sent[1].get("ismaster", None))
+        self.assertIsNone(self._sent[2].get("ismaster", None))
 
 
 if __name__ == "__main__":
diff --git a/test/test_hello_latched.py b/test/test_hello_latched.py
deleted file mode 100644
index 303686fe17..0000000000
--- a/test/test_hello_latched.py
+++ /dev/null
@@ -1,74 +0,0 @@
-import unittest
-from unittest.mock import Mock 
-from types import SimpleNamespace
-from pymongo.synchronous.pool import Connection 
-
-
-class TestHelloLatched(unittest.TestCase):
-    """
-    Test to Ensure that hello_ok remains latched
-    when the RTT thread switches to hello
-    """
-
-    def setUp(self):
-        self._sent = []
-
-    def create_connection(self) -> Connection:
-        """Returns a minimal connection object"""
-        conn = object.__new__(Connection)
-        conn.hello_ok = False
-        # Isolate this test to post-handshake hello_ok persistence
-        conn.performed_handshake = True
-        conn.opts = SimpleNamespace(
-            server_api = None,
-            load_balanced = False,
-            _credentials = None
-        )
-
-        return conn
-
-    def mock_connection_command(self, db, cmd, **kwargs):
-        """Returns mocked hello and ismaster results for conn.command"""
-        self._sent.append(cmd.copy())
-        if cmd.get("ismaster") == 1:
-            return {"ok":1, "helloOk": True, "ismaster": True, "maxWireVersion": 25}
-        return {"ok":1, "isWritablePrimary": True, "maxWireVersion": 25}
-
-
-    def test_hello_is_latched(self):
-        """
-        Regression Test for PYTHON-5904
-        Tests for connection hello_ok persistence when connection
-        Switches from ismaster to hello
-        """
-
-        conn = self.create_connection()
-        conn.command = Mock(side_effect=self.mock_connection_command)
-
-        # First hello
-        conn._hello(None, None)
-        # Verify hello_ok is True
-        self.assertTrue(conn.hello_ok)
-        # Verify command sent is ismaster
-        self.assertEqual(self._sent[0].get("ismaster"), 1)
-        self.assertEqual(self._sent[0].get("helloOk"), True)
-
-        # Second hello
-        conn._hello(None, None)
-        # Verify hello_ok has not changed
-        self.assertTrue(conn.hello_ok)
-        # Verify command sent is hello
-        self.assertEqual(self._sent[1].get("hello"), 1)
-        self.assertIsNone(self._sent[1].get("ismaster", None))
-
-        # Third hello
-        conn._hello(None, None)
-        # Verify connection continues to use hello
-        self.assertEqual(self._sent[2].get("hello"), 1)
-        self.assertIsNone(self._sent[1].get("ismaster", None))
-
-
-if __name__ == "__main__":
-    unittest.main()
-
-

From d6aad634f51858feffd1232d64779091fad80351 Mon Sep 17 00:00:00 2001
From: Ronan Merrick <ronan.merrick@mongodb.com>
Date: Wed, 1 Jul 2026 11:29:40 +0100
Subject: [PATCH 4/8] added synchronous files and improved comment

---
 pymongo/asynchronous/pool.py            |  3 +-
 pymongo/synchronous/pool.py             |  4 +-
 test/asynchronous/test_hello_latched.py | 22 +++----
 test/test_hello_latched.py              | 79 +++++++++++++++++++++++++
 4 files changed, 93 insertions(+), 15 deletions(-)
 create mode 100644 test/test_hello_latched.py

diff --git a/pymongo/asynchronous/pool.py b/pymongo/asynchronous/pool.py
index 8c8d7ca267..f0a32cebd4 100644
--- a/pymongo/asynchronous/pool.py
+++ b/pymongo/asynchronous/pool.py
@@ -294,7 +294,8 @@ async def _hello(
             hello.logical_session_timeout_minutes is not None and hello.is_readable
         )
         self.logical_session_timeout_minutes: Optional[int] = hello.logical_session_timeout_minutes
-        # PYTHON-5904
+        # hello_ok is set from helloOk, which is only returned from ismaster
+        # don't overwrite this when connection switches to hello
         self.hello_ok = self.hello_ok or hello.hello_ok
         self.is_repl = hello.server_type in (
             SERVER_TYPE.RSPrimary,
diff --git a/pymongo/synchronous/pool.py b/pymongo/synchronous/pool.py
index b3929b674a..5d76766464 100644
--- a/pymongo/synchronous/pool.py
+++ b/pymongo/synchronous/pool.py
@@ -294,7 +294,9 @@ def _hello(
             hello.logical_session_timeout_minutes is not None and hello.is_readable
         )
         self.logical_session_timeout_minutes: Optional[int] = hello.logical_session_timeout_minutes
-        self.hello_ok = hello.hello_ok
+        # hello_ok is set from helloOk, which is only returned from ismaster
+        # don't overwrite this when connection switches to hello
+        self.hello_ok = self.hello_ok or hello.hello_ok
         self.is_repl = hello.server_type in (
             SERVER_TYPE.RSPrimary,
             SERVER_TYPE.RSSecondary,
diff --git a/test/asynchronous/test_hello_latched.py b/test/asynchronous/test_hello_latched.py
index e173301c98..c989737f51 100644
--- a/test/asynchronous/test_hello_latched.py
+++ b/test/asynchronous/test_hello_latched.py
@@ -14,13 +14,16 @@
 
 """Test that connection continues to use hello after ismaster returns hello_ok"""
 
+from __future__ import annotations
+
 import unittest
-from unittest.mock import AsyncMock 
 from types import SimpleNamespace
-from pymongo.asynchronous.pool import AsyncConnection 
+from unittest.mock import AsyncMock
 
-class TestHelloLatched(unittest.IsolatedAsyncioTestCase):
+from pymongo.asynchronous.pool import AsyncConnection
 
+
+class TestHelloLatched(unittest.IsolatedAsyncioTestCase):
     def setUp(self):
         self._sent = []
 
@@ -29,11 +32,7 @@ def create_connection(self) -> AsyncConnection:
         conn = object.__new__(AsyncConnection)
         conn.hello_ok = False
         conn.performed_handshake = True
-        conn.opts = SimpleNamespace(
-            server_api = None,
-            load_balanced = False,
-            _credentials = None
-        )
+        conn.opts = SimpleNamespace(server_api=None, load_balanced=False, _credentials=None)
 
         return conn
 
@@ -41,9 +40,8 @@ async def mock_conn_command(self, db, cmd, **kwargs):
         """Returns mocked hello and ismaster results for conn.command"""
         self._sent.append(cmd.copy())
         if cmd.get("ismaster") == 1:
-            return {"ok":1, "helloOk": True, "ismaster": True, "maxWireVersion": 25}
-        return {"ok":1, "isWritablePrimary": True, "maxWireVersion": 25}
-
+            return {"ok": 1, "helloOk": True, "ismaster": True, "maxWireVersion": 25}
+        return {"ok": 1, "isWritablePrimary": True, "maxWireVersion": 25}
 
     async def test_hello_is_latched(self):
         """
@@ -79,5 +77,3 @@ async def test_hello_is_latched(self):
 
 if __name__ == "__main__":
     unittest.main()
-
-
diff --git a/test/test_hello_latched.py b/test/test_hello_latched.py
new file mode 100644
index 0000000000..421669d150
--- /dev/null
+++ b/test/test_hello_latched.py
@@ -0,0 +1,79 @@
+# Copyright 2022-present MongoDB, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Test that connection continues to use hello after ismaster returns hello_ok"""
+
+from __future__ import annotations
+
+import unittest
+from types import SimpleNamespace
+from unittest.mock import SyncMock
+
+from pymongo.synchronous.pool import Connection
+
+
+class TestHelloLatched(unittest.TestCase):
+    def setUp(self):
+        self._sent = []
+
+    def create_connection(self) -> Connection:
+        """Returns a minimal connection object for _hello"""
+        conn = object.__new__(Connection)
+        conn.hello_ok = False
+        conn.performed_handshake = True
+        conn.opts = SimpleNamespace(server_api=None, load_balanced=False, _credentials=None)
+
+        return conn
+
+    def mock_conn_command(self, db, cmd, **kwargs):
+        """Returns mocked hello and ismaster results for conn.command"""
+        self._sent.append(cmd.copy())
+        if cmd.get("ismaster") == 1:
+            return {"ok": 1, "helloOk": True, "ismaster": True, "maxWireVersion": 25}
+        return {"ok": 1, "isWritablePrimary": True, "maxWireVersion": 25}
+
+    def test_hello_is_latched(self):
+        """
+        Regression Test for PYTHON-5904
+        Tests for connection hello_ok persistence when connection
+        Switches from ismaster to hello
+        """
+        conn = self.create_connection()
+        conn.command = SyncMock(side_effect=self.mock_conn_command)
+
+        # First hello
+        conn._hello(None, None)
+        # Verify hello_ok is True
+        self.assertTrue(conn.hello_ok)
+        # Verify command sent is ismaster
+        self.assertEqual(self._sent[0].get("ismaster"), 1)
+        self.assertEqual(self._sent[0].get("helloOk"), True)
+
+        # Second hello
+        conn._hello(None, None)
+        # Verify hello_ok has not changed
+        self.assertTrue(conn.hello_ok)
+        # Verify command sent is hello
+        self.assertEqual(self._sent[1].get("hello"), 1)
+        self.assertIsNone(self._sent[1].get("ismaster", None))
+
+        # Third hello
+        conn._hello(None, None)
+        # Verify connection continues to use hello
+        self.assertEqual(self._sent[2].get("hello"), 1)
+        self.assertIsNone(self._sent[2].get("ismaster", None))
+
+
+if __name__ == "__main__":
+    unittest.main()

From 1c674b77a809128981d2dfa9d37ab334fc73df4d Mon Sep 17 00:00:00 2001
From: Ronan Merrick <ronan.merrick@mongodb.com>
Date: Thu, 2 Jul 2026 17:21:00 +0100
Subject: [PATCH 5/8] updated synchro configuration and generated synchronous
 test file

---
 test/asynchronous/test_hello_latched.py | 4 +++-
 test/test_hello_latched.py              | 8 +++++---
 tools/synchro.py                        | 2 ++
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/test/asynchronous/test_hello_latched.py b/test/asynchronous/test_hello_latched.py
index c989737f51..36657bb4fa 100644
--- a/test/asynchronous/test_hello_latched.py
+++ b/test/asynchronous/test_hello_latched.py
@@ -1,4 +1,4 @@
-# Copyright 2022-present MongoDB, Inc.
+# Copyright 2026-present MongoDB, Inc.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -22,6 +22,8 @@
 
 from pymongo.asynchronous.pool import AsyncConnection
 
+_IS_SYNC = False
+
 
 class TestHelloLatched(unittest.IsolatedAsyncioTestCase):
     def setUp(self):
diff --git a/test/test_hello_latched.py b/test/test_hello_latched.py
index 421669d150..a1d7d3b2ff 100644
--- a/test/test_hello_latched.py
+++ b/test/test_hello_latched.py
@@ -1,4 +1,4 @@
-# Copyright 2022-present MongoDB, Inc.
+# Copyright 2026-present MongoDB, Inc.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -18,10 +18,12 @@
 
 import unittest
 from types import SimpleNamespace
-from unittest.mock import SyncMock
+from unittest.mock import Mock
 
 from pymongo.synchronous.pool import Connection
 
+_IS_SYNC = True
+
 
 class TestHelloLatched(unittest.TestCase):
     def setUp(self):
@@ -50,7 +52,7 @@ def test_hello_is_latched(self):
         Switches from ismaster to hello
         """
         conn = self.create_connection()
-        conn.command = SyncMock(side_effect=self.mock_conn_command)
+        conn.command = Mock(side_effect=self.mock_conn_command)
 
         # First hello
         conn._hello(None, None)
diff --git a/tools/synchro.py b/tools/synchro.py
index 8132167e71..3cc2a44138 100644
--- a/tools/synchro.py
+++ b/tools/synchro.py
@@ -140,6 +140,7 @@
     "_async_create_connection": "_create_connection",
     "pymongo.asynchronous.srv_resolver._SrvResolver.get_hosts": "pymongo.synchronous.srv_resolver._SrvResolver.get_hosts",
     "dns.asyncresolver.resolve": "dns.resolver.resolve",
+    "AsyncMock": "Mock",
 }
 
 docstring_replacements: dict[tuple[str, str], str] = {
@@ -244,6 +245,7 @@ def async_only_test(f: Path) -> bool:
     "test_gridfs_spec.py",
     "test_handshake_unified.py",
     "test_heartbeat_monitoring.py",
+    "test_hello_latched.py",
     "test_index_management.py",
     "test_json_util_integration.py",
     "test_load_balancer.py",

From 1a3c11b861d2802f710cd9e455074be46b7eec5e Mon Sep 17 00:00:00 2001
From: Ronan Merrick <ronan.merrick@mongodb.com>
Date: Wed, 8 Jul 2026 19:59:00 +0100
Subject: [PATCH 6/8] changed test_hello_latched.py to use AsyncUnitTest

---
 test/asynchronous/test_hello_latched.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/asynchronous/test_hello_latched.py b/test/asynchronous/test_hello_latched.py
index 36657bb4fa..175635e3d4 100644
--- a/test/asynchronous/test_hello_latched.py
+++ b/test/asynchronous/test_hello_latched.py
@@ -19,13 +19,13 @@
 import unittest
 from types import SimpleNamespace
 from unittest.mock import AsyncMock
-
 from pymongo.asynchronous.pool import AsyncConnection
+from test.asynchronous import AsyncUnitTest
 
 _IS_SYNC = False
 
 
-class TestHelloLatched(unittest.IsolatedAsyncioTestCase):
+class TestHelloLatched(AsyncUnitTest):
     def setUp(self):
         self._sent = []
 

From 3f5e5971cf8c0cf76c418e8cb819957cd56448b2 Mon Sep 17 00:00:00 2001
From: Ronan Merrick <ronan.merrick@mongodb.com>
Date: Thu, 9 Jul 2026 19:23:02 +0100
Subject: [PATCH 7/8] narrowed unasync replacement for test_hello_latched.py

---
 test/asynchronous/test_hello_latched.py |  9 +++++++--
 test/test_hello_latched.py              | 11 ++++++++---
 tools/synchro.py                        |  2 +-
 3 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/test/asynchronous/test_hello_latched.py b/test/asynchronous/test_hello_latched.py
index 175635e3d4..38dc12f94b 100644
--- a/test/asynchronous/test_hello_latched.py
+++ b/test/asynchronous/test_hello_latched.py
@@ -18,7 +18,12 @@
 
 import unittest
 from types import SimpleNamespace
-from unittest.mock import AsyncMock
+
+# Use a test-specific alias here because a generic AsyncMock replacement caused
+# unintended rewrites in generated sync tests. Keeping the alias narrow limits
+# the unasync/synchro transform to this test.
+from unittest.mock import AsyncMock as AsyncLatchedHelloMock
+
 from pymongo.asynchronous.pool import AsyncConnection
 from test.asynchronous import AsyncUnitTest
 
@@ -52,7 +57,7 @@ async def test_hello_is_latched(self):
         Switches from ismaster to hello
         """
         conn = self.create_connection()
-        conn.command = AsyncMock(side_effect=self.mock_conn_command)
+        conn.command = AsyncLatchedHelloMock(side_effect=self.mock_conn_command)
 
         # First hello
         await conn._hello(None, None)
diff --git a/test/test_hello_latched.py b/test/test_hello_latched.py
index a1d7d3b2ff..6c05aa0b63 100644
--- a/test/test_hello_latched.py
+++ b/test/test_hello_latched.py
@@ -18,14 +18,19 @@
 
 import unittest
 from types import SimpleNamespace
-from unittest.mock import Mock
+
+# Use a test-specific alias here because a generic AsyncMock replacement caused
+# unintended rewrites in generated sync tests. Keeping the alias narrow limits
+# the unasync/synchro transform to this test.
+from unittest.mock import Mock as LatchedHelloMock
 
 from pymongo.synchronous.pool import Connection
+from test import UnitTest
 
 _IS_SYNC = True
 
 
-class TestHelloLatched(unittest.TestCase):
+class TestHelloLatched(UnitTest):
     def setUp(self):
         self._sent = []
 
@@ -52,7 +57,7 @@ def test_hello_is_latched(self):
         Switches from ismaster to hello
         """
         conn = self.create_connection()
-        conn.command = Mock(side_effect=self.mock_conn_command)
+        conn.command = LatchedHelloMock(side_effect=self.mock_conn_command)
 
         # First hello
         conn._hello(None, None)
diff --git a/tools/synchro.py b/tools/synchro.py
index 8b32f06c40..3764e53769 100644
--- a/tools/synchro.py
+++ b/tools/synchro.py
@@ -140,7 +140,7 @@
     "_async_create_connection": "_create_connection",
     "pymongo.asynchronous.srv_resolver._SrvResolver.get_hosts": "pymongo.synchronous.srv_resolver._SrvResolver.get_hosts",
     "dns.asyncresolver.resolve": "dns.resolver.resolve",
-    "AsyncMock": "Mock",
+    "AsyncLatchedHelloMock": "LatchedHelloMock",
 }
 
 docstring_replacements: dict[tuple[str, str], str] = {

From e7b22d57681941fdcae44dfa17840a8315a85f80 Mon Sep 17 00:00:00 2001
From: Ronan Merrick <ronan.merrick@mongodb.com>
Date: Fri, 10 Jul 2026 16:13:43 +0100
Subject: [PATCH 8/8] inlined mock_conn_command in test_hello_latched and
 removed the mock object

---
 test/asynchronous/test_hello_latched.py | 22 +++++++++-------------
 test/test_hello_latched.py              | 22 +++++++++-------------
 tools/synchro.py                        |  1 -
 3 files changed, 18 insertions(+), 27 deletions(-)

diff --git a/test/asynchronous/test_hello_latched.py b/test/asynchronous/test_hello_latched.py
index 38dc12f94b..20ad7cedff 100644
--- a/test/asynchronous/test_hello_latched.py
+++ b/test/asynchronous/test_hello_latched.py
@@ -19,11 +19,6 @@
 import unittest
 from types import SimpleNamespace
 
-# Use a test-specific alias here because a generic AsyncMock replacement caused
-# unintended rewrites in generated sync tests. Keeping the alias narrow limits
-# the unasync/synchro transform to this test.
-from unittest.mock import AsyncMock as AsyncLatchedHelloMock
-
 from pymongo.asynchronous.pool import AsyncConnection
 from test.asynchronous import AsyncUnitTest
 
@@ -43,21 +38,22 @@ def create_connection(self) -> AsyncConnection:
 
         return conn
 
-    async def mock_conn_command(self, db, cmd, **kwargs):
-        """Returns mocked hello and ismaster results for conn.command"""
-        self._sent.append(cmd.copy())
-        if cmd.get("ismaster") == 1:
-            return {"ok": 1, "helloOk": True, "ismaster": True, "maxWireVersion": 25}
-        return {"ok": 1, "isWritablePrimary": True, "maxWireVersion": 25}
-
     async def test_hello_is_latched(self):
         """
         Regression Test for PYTHON-5904
         Tests for connection hello_ok persistence when connection
         Switches from ismaster to hello
         """
+
+        async def mock_conn_command(db, cmd, **kwargs):
+            """Returns mocked hello and ismaster results for conn.command"""
+            self._sent.append(cmd.copy())
+            if cmd.get("ismaster") == 1:
+                return {"ok": 1, "helloOk": True, "ismaster": True, "maxWireVersion": 25}
+            return {"ok": 1, "isWritablePrimary": True, "maxWireVersion": 25}
+
         conn = self.create_connection()
-        conn.command = AsyncLatchedHelloMock(side_effect=self.mock_conn_command)
+        conn.command = mock_conn_command
 
         # First hello
         await conn._hello(None, None)
diff --git a/test/test_hello_latched.py b/test/test_hello_latched.py
index 6c05aa0b63..8bc8e995a6 100644
--- a/test/test_hello_latched.py
+++ b/test/test_hello_latched.py
@@ -19,11 +19,6 @@
 import unittest
 from types import SimpleNamespace
 
-# Use a test-specific alias here because a generic AsyncMock replacement caused
-# unintended rewrites in generated sync tests. Keeping the alias narrow limits
-# the unasync/synchro transform to this test.
-from unittest.mock import Mock as LatchedHelloMock
-
 from pymongo.synchronous.pool import Connection
 from test import UnitTest
 
@@ -43,21 +38,22 @@ def create_connection(self) -> Connection:
 
         return conn
 
-    def mock_conn_command(self, db, cmd, **kwargs):
-        """Returns mocked hello and ismaster results for conn.command"""
-        self._sent.append(cmd.copy())
-        if cmd.get("ismaster") == 1:
-            return {"ok": 1, "helloOk": True, "ismaster": True, "maxWireVersion": 25}
-        return {"ok": 1, "isWritablePrimary": True, "maxWireVersion": 25}
-
     def test_hello_is_latched(self):
         """
         Regression Test for PYTHON-5904
         Tests for connection hello_ok persistence when connection
         Switches from ismaster to hello
         """
+
+        def mock_conn_command(db, cmd, **kwargs):
+            """Returns mocked hello and ismaster results for conn.command"""
+            self._sent.append(cmd.copy())
+            if cmd.get("ismaster") == 1:
+                return {"ok": 1, "helloOk": True, "ismaster": True, "maxWireVersion": 25}
+            return {"ok": 1, "isWritablePrimary": True, "maxWireVersion": 25}
+
         conn = self.create_connection()
-        conn.command = LatchedHelloMock(side_effect=self.mock_conn_command)
+        conn.command = mock_conn_command
 
         # First hello
         conn._hello(None, None)
diff --git a/tools/synchro.py b/tools/synchro.py
index 3764e53769..f9c3f23c8c 100644
--- a/tools/synchro.py
+++ b/tools/synchro.py
@@ -140,7 +140,6 @@
     "_async_create_connection": "_create_connection",
     "pymongo.asynchronous.srv_resolver._SrvResolver.get_hosts": "pymongo.synchronous.srv_resolver._SrvResolver.get_hosts",
     "dns.asyncresolver.resolve": "dns.resolver.resolve",
-    "AsyncLatchedHelloMock": "LatchedHelloMock",
 }
 
 docstring_replacements: dict[tuple[str, str], str] = {