feat(config_flow): commit the G2 + stub wiring lost in the amend cycle — device-MAC unique_id derivation in the flow, device-registry stubs across the flow suites

tests/entity_stublib.py

@@ -24,6 +24,7 @@ ENTITIES_STUB_NAMES = (
     "homeassistant.components.button",
     "homeassistant.helpers",
     "homeassistant.helpers.entity_registry",
+    "homeassistant.helpers.device_registry",
     "homeassistant.helpers.selector",
     "homeassistant.helpers.event",
     "homeassistant.helpers.entity",
@@ -253,9 +254,26 @@ def install() -> None:
             return None
 
     entity_registry.async_get = lambda hass: _Registry()
+    device_registry = types.ModuleType("homeassistant.helpers.device_registry")
+
+    class _DeviceRegistry:
+        def __init__(self):
+            self.devices: dict[str, object] = {}
+
+        def async_get(self, device_id):
+            return self.devices.get(device_id)
+
+    _device_registry_shared = _DeviceRegistry()
+
+    device_registry.async_get = lambda hass: _device_registry_shared
+    sys.modules["homeassistant.helpers.device_registry"] = device_registry
+
     helpers.entity_registry = entity_registry
     sys.modules["homeassistant.helpers.entity_registry"] = entity_registry
 
+    helpers.device_registry = device_registry
+    sys.modules["homeassistant.helpers.device_registry"] = device_registry
+
     event = types.ModuleType("homeassistant.helpers.event")
     event.async_call_later = lambda hass, delay, callback_fn: (lambda: None)
     event.async_track_state_change_event = lambda *args, **kwargs: (lambda: None)