From 43d8c0bb6e07185ea46dd6c18de9bbfc2fc1a661 Mon Sep 17 00:00:00 2001
From: Yuxin Wang <yuxinwang.dev@gmail.com>
Date: Wed, 22 Jan 2025 23:10:52 -0500
Subject: [PATCH] Fallback to None for literal "Blank" serial number for
 APCUPSD integration (#136297)

* Fallback to None for Blank serial number

* Fix comments
---
 homeassistant/components/apcupsd/coordinator.py | 5 ++++-
 tests/components/apcupsd/test_config_flow.py    | 2 ++
 tests/components/apcupsd/test_init.py           | 8 ++++++--
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/homeassistant/components/apcupsd/coordinator.py b/homeassistant/components/apcupsd/coordinator.py
index 768e9605967..1ae12d8c4b0 100644
--- a/homeassistant/components/apcupsd/coordinator.py
+++ b/homeassistant/components/apcupsd/coordinator.py
@@ -44,7 +44,10 @@ class APCUPSdData(dict[str, str]):
     @property
     def serial_no(self) -> str | None:
         """Return the unique serial number of the UPS, if available."""
-        return self.get("SERIALNO")
+        sn = self.get("SERIALNO")
+        # We had user reports that some UPS models simply return "Blank" as serial number, in
+        # which case we fall back to `None` to indicate that it is actually not available.
+        return None if sn == "Blank" else sn
 
 
 class APCUPSdCoordinator(DataUpdateCoordinator[APCUPSdData]):
diff --git a/tests/components/apcupsd/test_config_flow.py b/tests/components/apcupsd/test_config_flow.py
index 88594260579..0b8386dbb5a 100644
--- a/tests/components/apcupsd/test_config_flow.py
+++ b/tests/components/apcupsd/test_config_flow.py
@@ -125,6 +125,8 @@ async def test_flow_works(hass: HomeAssistant) -> None:
         ({"UPSNAME": "Friendly Name"}, "Friendly Name"),
         ({"MODEL": "MODEL X"}, "MODEL X"),
         ({"SERIALNO": "ZZZZ"}, "ZZZZ"),
+        # Some models report "Blank" as serial number, which we should treat it as not reported.
+        ({"SERIALNO": "Blank"}, "APC UPS"),
         ({}, "APC UPS"),
     ],
 )
diff --git a/tests/components/apcupsd/test_init.py b/tests/components/apcupsd/test_init.py
index 723ec164eae..6bb94ca2948 100644
--- a/tests/components/apcupsd/test_init.py
+++ b/tests/components/apcupsd/test_init.py
@@ -31,6 +31,8 @@ from tests.common import MockConfigEntry, async_fire_time_changed
         # Does not contain either "SERIALNO" field.
         # We should _not_ create devices for the entities and their IDs will not have prefixes.
         MOCK_MINIMAL_STATUS,
+        # Some models report "Blank" as SERIALNO, but we should treat it as not reported.
+        MOCK_MINIMAL_STATUS | {"SERIALNO": "Blank"},
     ],
 )
 async def test_async_setup_entry(hass: HomeAssistant, status: OrderedDict) -> None:
@@ -41,7 +43,7 @@ async def test_async_setup_entry(hass: HomeAssistant, status: OrderedDict) -> No
     await async_init_integration(hass, status=status)
 
     prefix = ""
-    if "SERIALNO" in status:
+    if "SERIALNO" in status and status["SERIALNO"] != "Blank":
         prefix = slugify(status.get("UPSNAME", "APC UPS")) + "_"
 
     # Verify successful setup by querying the status sensor.
@@ -56,6 +58,8 @@ async def test_async_setup_entry(hass: HomeAssistant, status: OrderedDict) -> No
     [
         # We should not create device entries if SERIALNO is not reported.
         MOCK_MINIMAL_STATUS,
+        # Some models report "Blank" as SERIALNO, but we should treat it as not reported.
+        MOCK_MINIMAL_STATUS | {"SERIALNO": "Blank"},
         # We should set the device name to be the friendly UPSNAME field if available.
         MOCK_MINIMAL_STATUS | {"SERIALNO": "XXXX", "UPSNAME": "MyUPS"},
         # Otherwise, we should fall back to default device name --- "APC UPS".
@@ -71,7 +75,7 @@ async def test_device_entry(
     await async_init_integration(hass, status=status)
 
     # Verify device info is properly set up.
-    if "SERIALNO" not in status:
+    if "SERIALNO" not in status or status["SERIALNO"] == "Blank":
         assert len(device_registry.devices) == 0
         return