From a0d5fda4b6c502d877ed8ad1c3b440835606ac5f Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Sat, 30 Nov 2024 16:09:37 -0600
Subject: [PATCH] Reduce precision loss when converting HomeKit temperature
 (#131973)

---
 homeassistant/components/homekit/util.py          | 12 ++----------
 tests/components/homekit/test_type_thermostats.py | 10 +++++-----
 tests/components/homekit/test_util.py             |  8 +++++---
 3 files changed, 12 insertions(+), 18 deletions(-)

diff --git a/homeassistant/components/homekit/util.py b/homeassistant/components/homekit/util.py
index d540a88d6e67a..d339aa6aded34 100644
--- a/homeassistant/components/homekit/util.py
+++ b/homeassistant/components/homekit/util.py
@@ -434,20 +434,12 @@ def cleanup_name_for_homekit(name: str | None) -> str:
 
 def temperature_to_homekit(temperature: float, unit: str) -> float:
     """Convert temperature to Celsius for HomeKit."""
-    return round(
-        TemperatureConverter.convert(temperature, unit, UnitOfTemperature.CELSIUS), 1
-    )
+    return TemperatureConverter.convert(temperature, unit, UnitOfTemperature.CELSIUS)
 
 
 def temperature_to_states(temperature: float, unit: str) -> float:
     """Convert temperature back from Celsius to Home Assistant unit."""
-    return (
-        round(
-            TemperatureConverter.convert(temperature, UnitOfTemperature.CELSIUS, unit)
-            * 2
-        )
-        / 2
-    )
+    return TemperatureConverter.convert(temperature, UnitOfTemperature.CELSIUS, unit)
 
 
 def density_to_air_quality(density: float) -> int:
diff --git a/tests/components/homekit/test_type_thermostats.py b/tests/components/homekit/test_type_thermostats.py
index 8454610566b44..e99db8f6234aa 100644
--- a/tests/components/homekit/test_type_thermostats.py
+++ b/tests/components/homekit/test_type_thermostats.py
@@ -921,8 +921,8 @@ async def test_thermostat_fahrenheit(
     await hass.async_block_till_done()
     assert call_set_temperature[0]
     assert call_set_temperature[0].data[ATTR_ENTITY_ID] == entity_id
-    assert call_set_temperature[0].data[ATTR_TARGET_TEMP_HIGH] == 73.5
-    assert call_set_temperature[0].data[ATTR_TARGET_TEMP_LOW] == 68
+    assert call_set_temperature[0].data[ATTR_TARGET_TEMP_HIGH] == 73.4
+    assert call_set_temperature[0].data[ATTR_TARGET_TEMP_LOW] == 68.18
     assert len(events) == 1
     assert events[-1].data[ATTR_VALUE] == "CoolingThresholdTemperature to 23°C"
 
@@ -942,8 +942,8 @@ async def test_thermostat_fahrenheit(
     await hass.async_block_till_done()
     assert call_set_temperature[1]
     assert call_set_temperature[1].data[ATTR_ENTITY_ID] == entity_id
-    assert call_set_temperature[1].data[ATTR_TARGET_TEMP_HIGH] == 73.5
-    assert call_set_temperature[1].data[ATTR_TARGET_TEMP_LOW] == 71.5
+    assert call_set_temperature[1].data[ATTR_TARGET_TEMP_HIGH] == 73.4
+    assert call_set_temperature[1].data[ATTR_TARGET_TEMP_LOW] == 71.6
     assert len(events) == 2
     assert events[-1].data[ATTR_VALUE] == "HeatingThresholdTemperature to 22°C"
 
@@ -962,7 +962,7 @@ async def test_thermostat_fahrenheit(
     await hass.async_block_till_done()
     assert call_set_temperature[2]
     assert call_set_temperature[2].data[ATTR_ENTITY_ID] == entity_id
-    assert call_set_temperature[2].data[ATTR_TEMPERATURE] == 75.0
+    assert call_set_temperature[2].data[ATTR_TEMPERATURE] == 75.2
     assert len(events) == 3
     assert events[-1].data[ATTR_VALUE] == "TargetTemperature to 24.0°C"
 
diff --git a/tests/components/homekit/test_util.py b/tests/components/homekit/test_util.py
index e544362acc062..853db54b9926d 100644
--- a/tests/components/homekit/test_util.py
+++ b/tests/components/homekit/test_util.py
@@ -280,14 +280,16 @@ def test_cleanup_name_for_homekit() -> None:
 
 def test_temperature_to_homekit() -> None:
     """Test temperature conversion from HA to HomeKit."""
-    assert temperature_to_homekit(20.46, UnitOfTemperature.CELSIUS) == 20.5
-    assert temperature_to_homekit(92.1, UnitOfTemperature.FAHRENHEIT) == 33.4
+    assert temperature_to_homekit(20.46, UnitOfTemperature.CELSIUS) == 20.46
+    assert temperature_to_homekit(92.1, UnitOfTemperature.FAHRENHEIT) == pytest.approx(
+        33.388888888888886
+    )
 
 
 def test_temperature_to_states() -> None:
     """Test temperature conversion from HomeKit to HA."""
     assert temperature_to_states(20, UnitOfTemperature.CELSIUS) == 20.0
-    assert temperature_to_states(20.2, UnitOfTemperature.FAHRENHEIT) == 68.5
+    assert temperature_to_states(20.2, UnitOfTemperature.FAHRENHEIT) == 68.36
 
 
 def test_density_to_air_quality() -> None: