Warn when user tries run custom config flow (#24657)

tests/test_config_entries.py

@@ -5,7 +5,7 @@ from unittest.mock import MagicMock, patch
 
 import pytest
 
-from homeassistant import config_entries, data_entry_flow
+from homeassistant import config_entries, data_entry_flow, loader
 from homeassistant.core import callback
 from homeassistant.exceptions import ConfigEntryNotReady
 from homeassistant.setup import async_setup_component
@@ -934,3 +934,17 @@ async def test_entry_reload_error(hass, manager, state):
     assert len(async_setup_entry.mock_calls) == 0
 
     assert entry.state == state
+
+
+async def test_init_custom_integration(hass):
+    """Test initializing flow for custom integration."""
+    integration = loader.Integration(hass, 'custom_components.hue', None, {
+        'name': 'Hue',
+        'dependencies': [],
+        'requirements': [],
+        'domain': 'hue',
+    })
+    with pytest.raises(data_entry_flow.UnknownHandler):
+        with patch('homeassistant.loader.async_get_integration',
+                   return_value=mock_coro(integration)):
+            await hass.config_entries.flow.async_init('bla')

tests/test_loader.py

@@ -152,6 +152,16 @@ def test_integration_properties(hass):
     assert integration.domain == 'hue'
     assert integration.dependencies == ['test-dep']
     assert integration.requirements == ['test-req==1.0.0']
+    assert integration.is_built_in is True
+
+    integration = loader.Integration(
+        hass, 'custom_components.hue', None, {
+            'name': 'Philips Hue',
+            'domain': 'hue',
+            'dependencies': ['test-dep'],
+            'requirements': ['test-req==1.0.0'],
+        })
+    assert integration.is_built_in is False
 
 
 async def test_integrations_only_once(hass):