From f842640249ae065430592b266575f49896216d80 Mon Sep 17 00:00:00 2001
From: Robert Resch <robert@resch.dev>
Date: Wed, 26 Mar 2025 13:52:00 +0100
Subject: [PATCH] Add check that sensor state classes are used only with valid
 unit of measurements (#141444)

---
 homeassistant/components/sensor/__init__.py | 13 ++++++++
 homeassistant/components/sensor/const.py    |  5 ++++
 tests/components/sensor/test_init.py        | 33 +++++++++++++++++++++
 3 files changed, 51 insertions(+)

diff --git a/homeassistant/components/sensor/__init__.py b/homeassistant/components/sensor/__init__.py
index e3ee566a855..e06ee85cd03 100644
--- a/homeassistant/components/sensor/__init__.py
+++ b/homeassistant/components/sensor/__init__.py
@@ -44,6 +44,7 @@ from .const import (  # noqa: F401
     DEVICE_CLASSES_SCHEMA,
     DOMAIN,
     NON_NUMERIC_DEVICE_CLASSES,
+    STATE_CLASS_UNITS,
     STATE_CLASSES,
     STATE_CLASSES_SCHEMA,
     UNIT_CONVERTERS,
@@ -713,6 +714,18 @@ class SensorEntity(Entity, cached_properties=CACHED_PROPERTIES_WITH_ATTR_):
                 report_issue,
             )
 
+        # Validate unit of measurement used for sensors with a state class
+        if (
+            state_class
+            and (units := STATE_CLASS_UNITS.get(state_class)) is not None
+            and native_unit_of_measurement not in units
+        ):
+            raise ValueError(
+                f"Sensor {self.entity_id} ({type(self)}) is using native unit of "
+                f"measurement '{native_unit_of_measurement}' which is not a valid unit "
+                f"for the state class ('{state_class}') it is using; expected one of {units};"
+            )
+
         return value
 
     def _display_precision_or_none(self) -> int | None:
diff --git a/homeassistant/components/sensor/const.py b/homeassistant/components/sensor/const.py
index 916bd5cbd40..63af8e5bf52 100644
--- a/homeassistant/components/sensor/const.py
+++ b/homeassistant/components/sensor/const.py
@@ -699,3 +699,8 @@ DEVICE_CLASS_STATE_CLASSES: dict[SensorDeviceClass, set[SensorStateClass]] = {
     SensorDeviceClass.WIND_DIRECTION: {SensorStateClass.MEASUREMENT_ANGLE},
     SensorDeviceClass.WIND_SPEED: {SensorStateClass.MEASUREMENT},
 }
+
+
+STATE_CLASS_UNITS: dict[SensorStateClass | str, set[type[StrEnum] | str | None]] = {
+    SensorStateClass.MEASUREMENT_ANGLE: {DEGREE},
+}
diff --git a/tests/components/sensor/test_init.py b/tests/components/sensor/test_init.py
index b162200f95e..9666e29579b 100644
--- a/tests/components/sensor/test_init.py
+++ b/tests/components/sensor/test_init.py
@@ -24,6 +24,7 @@ from homeassistant.components.sensor import (
     async_rounded_state,
     async_update_suggested_units,
 )
+from homeassistant.components.sensor.const import STATE_CLASS_UNITS
 from homeassistant.config_entries import ConfigEntry, ConfigFlow
 from homeassistant.const import (
     ATTR_UNIT_OF_MEASUREMENT,
@@ -2005,6 +2006,7 @@ async def test_non_numeric_device_class_with_unit_of_measurement(
         SensorDeviceClass.VOLUME,
         SensorDeviceClass.WATER,
         SensorDeviceClass.WEIGHT,
+        SensorDeviceClass.WIND_DIRECTION,
         SensorDeviceClass.WIND_SPEED,
     ],
 )
@@ -2035,6 +2037,37 @@ async def test_device_classes_with_invalid_unit_of_measurement(
     ) in caplog.text
 
 
+@pytest.mark.parametrize(
+    "state_class",
+    [SensorStateClass.MEASUREMENT_ANGLE],
+)
+async def test_state_classes_with_invalid_unit_of_measurement(
+    hass: HomeAssistant,
+    caplog: pytest.LogCaptureFixture,
+    state_class: SensorStateClass,
+) -> None:
+    """Test error when unit of measurement is not valid for used state class."""
+    entity0 = MockSensor(
+        name="Test",
+        native_value="1.0",
+        state_class=state_class,
+        native_unit_of_measurement="INVALID!",
+    )
+    setup_test_component_platform(hass, sensor.DOMAIN, [entity0])
+    units = {
+        str(unit) if unit else "no unit of measurement"
+        for unit in STATE_CLASS_UNITS.get(state_class, set())
+    }
+    assert await async_setup_component(hass, "sensor", {"sensor": {"platform": "test"}})
+    await hass.async_block_till_done()
+
+    assert (
+        f"Sensor sensor.test ({entity0.__class__}) is using native unit of "
+        "measurement 'INVALID!' which is not a valid unit "
+        f"for the state class ('{state_class}') it is using; expected one of {units};"
+    ) in caplog.text
+
+
 @pytest.mark.parametrize(
     ("device_class", "state_class", "unit"),
     [