From cf2d927f141e195b1c3ca15ca6c5e625994e208f Mon Sep 17 00:00:00 2001
From: Paulus Schoutsen <balloob@gmail.com>
Date: Tue, 20 Aug 2019 10:46:51 -0700
Subject: [PATCH] Use init_subclass for Config Entries (#26059)

* Use init_subclass for Config Entries

* Ignore type
---
 homeassistant/components/hue/config_flow.py |  3 +-
 homeassistant/components/met/config_flow.py |  3 +-
 homeassistant/config_entries.py             |  6 ++++
 tests/test_config_entries.py                | 35 +++++++++++----------
 4 files changed, 26 insertions(+), 21 deletions(-)

diff --git a/homeassistant/components/hue/config_flow.py b/homeassistant/components/hue/config_flow.py
index 1d058d84b61..0b0e3723b13 100644
--- a/homeassistant/components/hue/config_flow.py
+++ b/homeassistant/components/hue/config_flow.py
@@ -44,8 +44,7 @@ def _find_username_from_config(hass, filename):
             return None
 
 
-@config_entries.HANDLERS.register(DOMAIN)
-class HueFlowHandler(config_entries.ConfigFlow):
+class HueFlowHandler(config_entries.ConfigFlow, domain=DOMAIN):
     """Handle a Hue config flow."""
 
     VERSION = 1
diff --git a/homeassistant/components/met/config_flow.py b/homeassistant/components/met/config_flow.py
index e903c717e64..795ba57d988 100644
--- a/homeassistant/components/met/config_flow.py
+++ b/homeassistant/components/met/config_flow.py
@@ -17,8 +17,7 @@ def configured_instances(hass):
     )
 
 
-@config_entries.HANDLERS.register(DOMAIN)
-class MetFlowHandler(config_entries.ConfigFlow):
+class MetFlowHandler(config_entries.ConfigFlow, domain=DOMAIN):
     """Config flow for Met component."""
 
     VERSION = 1
diff --git a/homeassistant/config_entries.py b/homeassistant/config_entries.py
index 87bce1a870c..2e1fbea14d1 100644
--- a/homeassistant/config_entries.py
+++ b/homeassistant/config_entries.py
@@ -670,6 +670,12 @@ async def _old_conf_migrator(old_config):
 class ConfigFlow(data_entry_flow.FlowHandler):
     """Base class for config flows with some helpers."""
 
+    def __init_subclass__(cls, domain=None, **kwargs):
+        """Initialize a subclass, register if possible."""
+        super().__init_subclass__(**kwargs)  # type: ignore
+        if domain is not None:
+            HANDLERS.register(domain)(cls)
+
     CONNECTION_CLASS = CONN_CLASS_UNKNOWN
 
     @staticmethod
diff --git a/tests/test_config_entries.py b/tests/test_config_entries.py
index 6c1b00693dd..ca6872a7a2c 100644
--- a/tests/test_config_entries.py
+++ b/tests/test_config_entries.py
@@ -521,31 +521,32 @@ async def test_discovery_notification(hass):
     mock_entity_platform(hass, "config_flow.test", None)
     await async_setup_component(hass, "persistent_notification", {})
 
-    class TestFlow(config_entries.ConfigFlow):
-        VERSION = 5
+    with patch.dict(config_entries.HANDLERS):
 
-        async def async_step_discovery(self, user_input=None):
-            if user_input is not None:
-                return self.async_create_entry(
-                    title="Test Title", data={"token": "abcd"}
-                )
-            return self.async_show_form(step_id="discovery")
+        class TestFlow(config_entries.ConfigFlow, domain="test"):
+            VERSION = 5
+
+            async def async_step_discovery(self, user_input=None):
+                if user_input is not None:
+                    return self.async_create_entry(
+                        title="Test Title", data={"token": "abcd"}
+                    )
+                return self.async_show_form(step_id="discovery")
 
-    with patch.dict(config_entries.HANDLERS, {"test": TestFlow}):
         result = await hass.config_entries.flow.async_init(
             "test", context={"source": config_entries.SOURCE_DISCOVERY}
         )
 
-    await hass.async_block_till_done()
-    state = hass.states.get("persistent_notification.config_entry_discovery")
-    assert state is not None
+        await hass.async_block_till_done()
+        state = hass.states.get("persistent_notification.config_entry_discovery")
+        assert state is not None
 
-    result = await hass.config_entries.flow.async_configure(result["flow_id"], {})
-    assert result["type"] == data_entry_flow.RESULT_TYPE_CREATE_ENTRY
+        result = await hass.config_entries.flow.async_configure(result["flow_id"], {})
+        assert result["type"] == data_entry_flow.RESULT_TYPE_CREATE_ENTRY
 
-    await hass.async_block_till_done()
-    state = hass.states.get("persistent_notification.config_entry_discovery")
-    assert state is None
+        await hass.async_block_till_done()
+        state = hass.states.get("persistent_notification.config_entry_discovery")
+        assert state is None
 
 
 async def test_discovery_notification_not_created(hass):