From 863b63d75e5c312cd3eb6744776f835b8401062c Mon Sep 17 00:00:00 2001
From: Erik Montnemery <erik@montnemery.com>
Date: Mon, 7 Sep 2020 04:08:50 +0200
Subject: [PATCH] Fix handling of device registry defaults (#39688)

---
 homeassistant/helpers/device_registry.py | 13 +++--
 tests/helpers/test_device_registry.py    | 61 +++++++++++++++++++++++-
 2 files changed, 65 insertions(+), 9 deletions(-)

diff --git a/homeassistant/helpers/device_registry.py b/homeassistant/helpers/device_registry.py
index 7c990aa397d..1dff2ef9483 100644
--- a/homeassistant/helpers/device_registry.py
+++ b/homeassistant/helpers/device_registry.py
@@ -239,15 +239,14 @@ class DeviceRegistry:
                 device = deleted_device.to_device_entry()
             self._add_device(device)
 
-        else:
-            if default_manufacturer and not device.manufacturer:
-                manufacturer = default_manufacturer
+        if default_manufacturer is not _UNDEF and device.manufacturer is None:
+            manufacturer = default_manufacturer
 
-            if default_model and not device.model:
-                model = default_model
+        if default_model is not _UNDEF and device.model is None:
+            model = default_model
 
-            if default_name and not device.name:
-                name = default_name
+        if default_name is not _UNDEF and device.name is None:
+            name = default_name
 
         if via_device is not None:
             via = self.async_get_device({via_device}, set())
diff --git a/tests/helpers/test_device_registry.py b/tests/helpers/test_device_registry.py
index 5b671dce134..7c9e8a6e262 100644
--- a/tests/helpers/test_device_registry.py
+++ b/tests/helpers/test_device_registry.py
@@ -841,8 +841,8 @@ async def test_restore_simple_device(hass, registry, update_events):
     assert update_events[3]["device_id"] == entry3.id
 
 
-async def test_get_or_create_sets_default_values(hass, registry):
-    """Make sure we do not duplicate entries."""
+async def test_get_or_create_empty_then_set_default_values(hass, registry):
+    """Test creating an entry, then setting default name, model, manufacturer."""
     entry = registry.async_get_or_create(
         identifiers={("bridgeid", "0123")}, config_entry_id="1234"
     )
@@ -871,3 +871,60 @@ async def test_get_or_create_sets_default_values(hass, registry):
     assert entry.name == "default name 1"
     assert entry.model == "default model 1"
     assert entry.manufacturer == "default manufacturer 1"
+
+
+async def test_get_or_create_empty_then_update(hass, registry):
+    """Test creating an entry, then setting name, model, manufacturer."""
+    entry = registry.async_get_or_create(
+        identifiers={("bridgeid", "0123")}, config_entry_id="1234"
+    )
+    assert entry.name is None
+    assert entry.model is None
+    assert entry.manufacturer is None
+
+    entry = registry.async_get_or_create(
+        config_entry_id="1234",
+        identifiers={("bridgeid", "0123")},
+        name="name 1",
+        model="model 1",
+        manufacturer="manufacturer 1",
+    )
+    assert entry.name == "name 1"
+    assert entry.model == "model 1"
+    assert entry.manufacturer == "manufacturer 1"
+
+    entry = registry.async_get_or_create(
+        config_entry_id="1234",
+        identifiers={("bridgeid", "0123")},
+        default_name="default name 1",
+        default_model="default model 1",
+        default_manufacturer="default manufacturer 1",
+    )
+    assert entry.name == "name 1"
+    assert entry.model == "model 1"
+    assert entry.manufacturer == "manufacturer 1"
+
+
+async def test_get_or_create_sets_default_values(hass, registry):
+    """Test creating an entry, then setting default name, model, manufacturer."""
+    entry = registry.async_get_or_create(
+        config_entry_id="1234",
+        identifiers={("bridgeid", "0123")},
+        default_name="default name 1",
+        default_model="default model 1",
+        default_manufacturer="default manufacturer 1",
+    )
+    assert entry.name == "default name 1"
+    assert entry.model == "default model 1"
+    assert entry.manufacturer == "default manufacturer 1"
+
+    entry = registry.async_get_or_create(
+        config_entry_id="1234",
+        identifiers={("bridgeid", "0123")},
+        default_name="default name 2",
+        default_model="default model 2",
+        default_manufacturer="default manufacturer 2",
+    )
+    assert entry.name == "default name 1"
+    assert entry.model == "default model 1"
+    assert entry.manufacturer == "default manufacturer 1"