Mark mqtt as integration with single config entry (#128202)

homeassistant/components/mqtt/config_flow.py

@@ -343,9 +343,6 @@ class FlowHandler(ConfigFlow, domain=DOMAIN):
         self, user_input: dict[str, Any] | None = None
     ) -> ConfigFlowResult:
         """Handle a flow initialized by the user."""
-        if self._async_current_entries():
-            return self.async_abort(reason="single_instance_allowed")
-
         if is_hassio(self.hass):
             # Offer to set up broker add-on if supervisor is available
             self._addon_manager = get_addon_manager(self.hass)

homeassistant/components/mqtt/manifest.json

@@ -7,5 +7,6 @@
   "documentation": "https://www.home-assistant.io/integrations/mqtt",
   "iot_class": "local_push",
   "quality_scale": "platinum",
-  "requirements": ["paho-mqtt==1.6.1"]
+  "requirements": ["paho-mqtt==1.6.1"],
+  "single_config_entry": true
 }

tests/components/mqtt/test_config_flow.py

@@ -420,7 +420,7 @@ async def test_hassio_already_configured(hass: HomeAssistant) -> None:
         "mqtt", context={"source": config_entries.SOURCE_HASSIO}
     )
     assert result["type"] is FlowResultType.ABORT
-    assert result["reason"] == "already_configured"
+    assert result["reason"] == "single_instance_allowed"
 
 
 async def test_hassio_ignored(hass: HomeAssistant) -> None: