Do async_setup_platform in background (#36244)

Co-authored-by: J. Nick Koston <nick@koston.org>

tests/components/homeassistant/test_scene.py

@@ -39,6 +39,7 @@ async def test_apply_service(hass):
     """Test the apply service."""
     assert await async_setup_component(hass, "scene", {})
     assert await async_setup_component(hass, "light", {"light": {"platform": "demo"}})
+    await hass.async_block_till_done()
 
     assert await hass.services.async_call(
         "scene", "apply", {"entities": {"light.bed_light": "off"}}, blocking=True
@@ -83,6 +84,7 @@ async def test_create_service(hass, caplog):
         "scene",
         {"scene": {"name": "hallo_2", "entities": {"light.kitchen": "on"}}},
     )
+    await hass.async_block_till_done()
     assert hass.states.get("scene.hallo") is None
     assert hass.states.get("scene.hallo_2") is not None
 
@@ -155,6 +157,7 @@ async def test_create_service(hass, caplog):
 async def test_snapshot_service(hass, caplog):
     """Test the snapshot option."""
     assert await async_setup_component(hass, "scene", {"scene": {}})
+    await hass.async_block_till_done()
     hass.states.async_set("light.my_light", "on", {"hs_color": (345, 75)})
     assert hass.states.get("scene.hallo") is None
 
@@ -212,6 +215,7 @@ async def test_snapshot_service(hass, caplog):
 async def test_ensure_no_intersection(hass):
     """Test that entities and snapshot_entities do not overlap."""
     assert await async_setup_component(hass, "scene", {"scene": {}})
+    await hass.async_block_till_done()
 
     with pytest.raises(vol.MultipleInvalid) as ex:
         assert await hass.services.async_call(
@@ -245,6 +249,7 @@ async def test_scenes_with_entity(hass):
             ]
         },
     )
+    await hass.async_block_till_done()
 
     assert sorted(ha_scene.scenes_with_entity(hass, "light.kitchen")) == [
         "scene.scene_1",
@@ -268,6 +273,7 @@ async def test_entities_in_scene(hass):
             ]
         },
     )
+    await hass.async_block_till_done()
 
     for scene_id, entities in (
         ("scene.scene_1", ["light.kitchen"]),
@@ -297,6 +303,7 @@ async def test_config(hass):
             ]
         },
     )
+    await hass.async_block_till_done()
 
     icon = hass.states.get("scene.scene_icon")
     assert icon is not None