Add config entry for Sonos + Cast (#14955)

* Add config entry for Sonos

* Lint

* Use add_job

* Add Cast config entry

* Lint

* Rename DOMAIN import

* Mock pychromecast in test

tests/components/cast/test_init.py

@@ -0,0 +1,22 @@
+"""Tests for the Cast config flow."""
+from unittest.mock import patch
+
+from homeassistant import data_entry_flow
+from homeassistant.components import cast
+
+from tests.common import MockDependency, mock_coro
+
+
+async def test_creating_entry_sets_up_media_player(hass):
+    """Test setting up Cast loads the media player."""
+    with patch('homeassistant.components.media_player.cast.async_setup_entry',
+               return_value=mock_coro(True)) as mock_setup, \
+            MockDependency('pychromecast', 'discovery'), \
+            patch('pychromecast.discovery.discover_chromecasts',
+                  return_value=True):
+        result = await hass.config_entries.flow.async_init(cast.DOMAIN)
+        assert result['type'] == data_entry_flow.RESULT_TYPE_CREATE_ENTRY
+
+        await hass.async_block_till_done()
+
+    assert len(mock_setup.mock_calls) == 1