Set up todo frontend resources when first platform is set up

homeassistant/components/todo/__init__.py

@@ -27,7 +27,7 @@ from homeassistant.exceptions import HomeAssistantError, ServiceValidationError
 from homeassistant.helpers import config_validation as cv
 from homeassistant.helpers.entity import Entity
 from homeassistant.helpers.entity_component import EntityComponent
-from homeassistant.helpers.typing import ConfigType
+from homeassistant.helpers.typing import ConfigType, DiscoveryInfoType
 from homeassistant.util import dt as dt_util
 
 from .const import (
@@ -120,16 +120,10 @@ def _validate_supported_features(
 
 async def async_setup(hass: HomeAssistant, config: ConfigType) -> bool:
     """Set up Todo entities."""
-    component = hass.data[DATA_COMPONENT] = EntityComponent[TodoListEntity](
+    component = hass.data[DATA_COMPONENT] = TodoEntityComponent(
         _LOGGER, DOMAIN, hass, SCAN_INTERVAL
     )
 
-    frontend.async_register_built_in_panel(hass, "todo", "todo", "mdi:clipboard-list")
-
-    websocket_api.async_register_command(hass, websocket_handle_subscribe_todo_items)
-    websocket_api.async_register_command(hass, websocket_handle_todo_item_list)
-    websocket_api.async_register_command(hass, websocket_handle_todo_item_move)
-
     component.async_register_entity_service(
         TodoServices.ADD_ITEM,
         vol.All(
@@ -318,6 +312,52 @@ class TodoListEntity(Entity, cached_properties=CACHED_PROPERTIES_WITH_ATTR_):
         self.async_update_listeners()
 
 
+class TodoEntityComponent(EntityComponent[TodoListEntity]):
+    """To-do entity component.
+
+    Sets up frontend resources and websocket API when the first platform is added.
+    """
+
+    _frontend_loaded: bool = False
+
+    async def async_setup_entry(self, config_entry: ConfigEntry) -> bool:
+        """Set up a config entry."""
+        result = await super().async_setup_entry(config_entry)
+
+        if not self._frontend_loaded:
+            self._register_frontend_resources()
+
+        return result
+
+    async def async_setup_platform(
+        self,
+        platform_type: str,
+        platform_config: ConfigType,
+        discovery_info: DiscoveryInfoType | None = None,
+    ) -> None:
+        """Set up a platform for this component."""
+        await super().async_setup_platform(
+            platform_type, platform_config, discovery_info
+        )
+
+        if not self._frontend_loaded:
+            self._register_frontend_resources()
+
+    def _register_frontend_resources(self) -> None:
+        """Register frontend resources for to-do."""
+        self._frontend_loaded = True
+
+        frontend.async_register_built_in_panel(
+            self.hass, "todo", "todo", "mdi:clipboard-list"
+        )
+
+        websocket_api.async_register_command(
+            self.hass, websocket_handle_subscribe_todo_items
+        )
+        websocket_api.async_register_command(self.hass, websocket_handle_todo_item_list)
+        websocket_api.async_register_command(self.hass, websocket_handle_todo_item_move)
+
+
 @websocket_api.websocket_command(
     {
         vol.Required("type"): "todo/item/subscribe",

tests/components/todo/test_init.py

@@ -2,6 +2,7 @@
 
 import datetime
 from typing import Any
+from unittest.mock import AsyncMock
 import zoneinfo
 
 import pytest
@@ -22,7 +23,7 @@ from homeassistant.components.todo import (
     TodoServices,
 )
 from homeassistant.config_entries import ConfigEntryState
-from homeassistant.const import ATTR_ENTITY_ID, ATTR_SUPPORTED_FEATURES
+from homeassistant.const import ATTR_ENTITY_ID, ATTR_SUPPORTED_FEATURES, CONF_PLATFORM
 from homeassistant.core import HomeAssistant
 from homeassistant.exceptions import (
     HomeAssistantError,
@@ -33,6 +34,7 @@ from homeassistant.setup import async_setup_component
 
 from . import create_mock_platform
 
+from tests.common import MockPlatform, mock_platform
 from tests.typing import WebSocketGenerator
 
 ITEM_1 = {
@@ -1299,3 +1301,47 @@ async def test_async_subscribe_updates(
     unsub()
     test_entity.async_write_ha_state()
     assert len(received_updates) == 4
+
+
+async def test_frontend_resources_registered_after_first_config_entry_setup(
+    hass: HomeAssistant,
+) -> None:
+    """Test that frontend resources are registered after the first config entry is set up."""
+    await async_setup_component(hass, "http", {})
+    assert "frontend_panels" not in hass.data
+    assert "websocket_api" not in hass.data
+
+    assert await async_setup_component(hass, DOMAIN, {DOMAIN: {CONF_PLATFORM: "test"}})
+    assert "frontend_panels" not in hass.data
+    assert "websocket_api" not in hass.data
+
+    await create_mock_platform(hass, [])
+    assert set(hass.data["frontend_panels"]) == {"todo"}
+    assert set(hass.data["websocket_api"]) == {
+        "todo/item/list",
+        "todo/item/move",
+        "todo/item/subscribe",
+    }
+
+
+async def test_frontend_resources_registered_after_first_platform_setup(
+    hass: HomeAssistant,
+) -> None:
+    """Test that frontend resources are registered after the first platform is set up."""
+    mock_platform(
+        hass,
+        f"test.{DOMAIN}",
+        MockPlatform(async_setup_platform=AsyncMock()),
+    )
+
+    await async_setup_component(hass, "http", {})
+    assert "frontend_panels" not in hass.data
+    assert "websocket_api" not in hass.data
+
+    assert await async_setup_component(hass, DOMAIN, {DOMAIN: {CONF_PLATFORM: "test"}})
+    assert set(hass.data["frontend_panels"]) == {"todo"}
+    assert set(hass.data["websocket_api"]) == {
+        "todo/item/list",
+        "todo/item/move",
+        "todo/item/subscribe",
+    }