MQTT-FIX-T01: make main MQTT client lifecycle idempotent

tests/test_mqtt_subscribe.py

@@ -143,7 +143,7 @@ def test_unsubscribe_unknown_topic_is_noop() -> None:
 # ---------------------------------------------------------------------------
 
 
-def _extract_on_message(manager: MqttManager, settings) -> object:
+def _extract_on_message(manager: MqttManager, settings) -> tuple[object, MagicMock]:
     """Connect with a mocked paho client and return the on_message callback that
     was registered on the client mock."""
     mock_client = MagicMock()
@@ -153,7 +153,7 @@ def _extract_on_message(manager: MqttManager, settings) -> object:
         manager.connect(settings)
 
     # The callback was assigned as: client.on_message = _on_message
-    return mock_client.on_message
+    return mock_client.on_message, mock_client
 
 
 def test_on_message_dispatches_to_registered_handler() -> None:
@@ -168,10 +168,10 @@ def test_on_message_dispatches_to_registered_handler() -> None:
 
     manager.subscribe("dsmr/json", handler)
 
-    on_message = _extract_on_message(manager, settings)
+    on_message, client = _extract_on_message(manager, settings)
 
     msg = _make_mqtt_message("dsmr/json", b'{"id": 1}')
-    on_message(MagicMock(), None, msg)  # simulate paho calling the callback
+    on_message(client, None, msg)  # simulate paho calling the callback
 
     assert received_payloads == [b'{"id": 1}']
 
@@ -183,11 +183,11 @@ def test_on_message_ignores_unknown_topic() -> None:
     handler = MagicMock()
     manager.subscribe("other/topic", handler)
 
-    on_message = _extract_on_message(manager, settings)
+    on_message, client = _extract_on_message(manager, settings)
 
     msg = _make_mqtt_message("unknown/topic", b"data")
     # Must not raise
-    on_message(MagicMock(), None, msg)
+    on_message(client, None, msg)
 
     handler.assert_not_called()
 
@@ -201,11 +201,11 @@ def test_on_message_swallows_handler_exception() -> None:
         raise RuntimeError("handler exploded")
 
     manager.subscribe("dsmr/json", bad_handler)
-    on_message = _extract_on_message(manager, settings)
+    on_message, client = _extract_on_message(manager, settings)
 
     msg = _make_mqtt_message("dsmr/json", b"{}")
     # This must not raise
-    on_message(MagicMock(), None, msg)
+    on_message(client, None, msg)
 
 
 def test_on_message_does_not_crash_on_handler_exception_multiple_calls() -> None:
@@ -221,13 +221,13 @@ def test_on_message_does_not_crash_on_handler_exception_multiple_calls() -> None
             raise ValueError("first call fails")
 
     manager.subscribe("dsmr/json", flaky_handler)
-    on_message = _extract_on_message(manager, settings)
+    on_message, client = _extract_on_message(manager, settings)
 
     msg1 = _make_mqtt_message("dsmr/json", b"first")
     msg2 = _make_mqtt_message("dsmr/json", b"second")
 
-    on_message(MagicMock(), None, msg1)  # should not raise despite exception in handler
-    on_message(MagicMock(), None, msg2)  # handler called again
+    on_message(client, None, msg1)  # should not raise despite exception in handler
+    on_message(client, None, msg2)  # handler called again
 
     assert call_count[0] == 2