handle the case asyncore isn't available

since asyncore isn't available in python 3.12,
we should be gracfully handle it, and enable any other event
loop implementions to work

Author: fruch

tests/integration/standard/test_connection.py

@@ -26,8 +26,12 @@
 
 from cassandra import ConsistencyLevel, OperationTimedOut
 from cassandra.cluster import NoHostAvailable, ConnectionShutdown, ExecutionProfile, EXEC_PROFILE_DEFAULT
-import cassandra.io.asyncorereactor
-from cassandra.io.asyncorereactor import AsyncoreConnection
+
+try:
+    from cassandra.io.asyncorereactor import AsyncoreConnection
+except ImportError:
+    AsyncoreConnection = None
+
 from cassandra.protocol import QueryMessage
 from cassandra.connection import Connection
 from cassandra.policies import HostFilterPolicy, RoundRobinPolicy, HostStateListener

tests/integration/standard/test_scylla_cloud.py

@@ -6,13 +6,19 @@
 
 from tests.integration import use_cluster
 from cassandra.cluster import Cluster, TwistedConnection
-from cassandra.io.asyncorereactor import AsyncoreConnection
+
+
 from cassandra.io.libevreactor import LibevConnection
 from cassandra.io.geventreactor import GeventConnection
 from cassandra.io.eventletreactor import EventletConnection
 from cassandra.io.asyncioreactor import AsyncioConnection
+supported_connection_classes = [LibevConnection, TwistedConnection]
+try:
+    from cassandra.io.asyncorereactor import AsyncoreConnection
+    supported_connection_classes += [AsyncoreConnection]
+except ImportError:
+    pass
 
-supported_connection_classes = [AsyncoreConnection, LibevConnection, TwistedConnection]
 # need to run them with specific configuration like `gevent.monkey.patch_all()` or under async functions
 unsupported_connection_classes = [GeventConnection, AsyncioConnection, EventletConnection]