build: harden controller v2 runtime

tests/test_mqtt_adapter.py

@@ -32,6 +32,7 @@ class FakeClient:
         self.acks = []
         self.suppress_exceptions = False
         self.connect_error = None
+        self.connect_result = None
         self.loop_result = mqtt.MQTT_ERR_SUCCESS
         self.publish_acknowledged = None
         self.publish_hook = None
@@ -52,7 +53,7 @@ class FakeClient:
         self.calls.append(("connect_async", args, kwargs))
         if self.connect_error is not None:
             raise self.connect_error
-        return mqtt.MQTT_ERR_SUCCESS
+        return self.connect_result
 
     def connect(self, *args, **kwargs):
         self.calls.append(("connect", args, kwargs))
@@ -123,6 +124,14 @@ class MqttAdapterTests(unittest.TestCase):
         self.assertEqual(connect[1], ("broker", 1884))
         self.assertEqual(connect[2], {"keepalive": 30})
 
+    def test_paho_two_connect_async_none_starts_network_loop(self):
+        self.client.connect_result = None
+        self.adapter.start()
+
+        self.assertTrue(self.adapter.started)
+        self.assertIn("loop_start", [call[0] for call in self.client.calls])
+        self.assertIsNone(self.adapter.last_error)
+
     def test_initial_setup_oserror_does_not_escape_startup(self):
         self.client.connect_error = OSError("network unreachable")
         self.adapter.start()