Avoid regex for negative zero check in sensor (#95691)

* Avoid regex for negative zero check in sensor

We can avoid calling the regex for every sensor value
since most of the time values are not negative zero

* tweak

* tweak

* Apply suggestions from code review

* simpler

* cover

* safer and still fast

* safer and still fast

* prep for py3.11

* fix check

* add missing cover

* more coverage

* coverage

* coverage

homeassistant/components/sensor/__init__.py

@@ -10,6 +10,7 @@ from decimal import Decimal, InvalidOperation as DecimalInvalidOperation
 import logging
 from math import ceil, floor, log10
 import re
+import sys
 from typing import Any, Final, cast, final
 
 from typing_extensions import Self
@@ -92,6 +93,8 @@ ENTITY_ID_FORMAT: Final = DOMAIN + ".{}"
 
 NEGATIVE_ZERO_PATTERN = re.compile(r"^-(0\.?0*)$")
 
+PY_311 = sys.version_info >= (3, 11, 0)
+
 SCAN_INTERVAL: Final = timedelta(seconds=30)
 
 __all__ = [
@@ -638,10 +641,12 @@ class SensorEntity(Entity):
                 )
                 precision = precision + floor(ratio_log)
 
-                value = f"{converted_numerical_value:.{precision}f}"
+                if PY_311:
-                # This can be replaced with adding the z option when we drop support for
+                    value = f"{converted_numerical_value:z.{precision}f}"
-                # Python 3.10
+                else:
-                value = NEGATIVE_ZERO_PATTERN.sub(r"\1", value)
+                    value = f"{converted_numerical_value:.{precision}f}"
+                    if value.startswith("-0") and NEGATIVE_ZERO_PATTERN.match(value):
+                        value = value[1:]
             else:
                 value = converted_numerical_value
 
@@ -883,29 +888,31 @@ def async_update_suggested_units(hass: HomeAssistant) -> None:
         )
 
 
+def _display_precision(hass: HomeAssistant, entity_id: str) -> int | None:
+    """Return the display precision."""
+    if not (entry := er.async_get(hass).async_get(entity_id)) or not (
+        sensor_options := entry.options.get(DOMAIN)
+    ):
+        return None
+    if (display_precision := sensor_options.get("display_precision")) is not None:
+        return cast(int, display_precision)
+    return sensor_options.get("suggested_display_precision")
+
+
 @callback
 def async_rounded_state(hass: HomeAssistant, entity_id: str, state: State) -> str:
     """Return the state rounded for presentation."""
-
-    def display_precision() -> int | None:
-        """Return the display precision."""
-        if not (entry := er.async_get(hass).async_get(entity_id)) or not (
-            sensor_options := entry.options.get(DOMAIN)
-        ):
-            return None
-        if (display_precision := sensor_options.get("display_precision")) is not None:
-            return cast(int, display_precision)
-        return sensor_options.get("suggested_display_precision")
-
     value = state.state
-    if (precision := display_precision()) is None:
+    if (precision := _display_precision(hass, entity_id)) is None:
         return value
 
     with suppress(TypeError, ValueError):
         numerical_value = float(value)
-        value = f"{numerical_value:.{precision}f}"
+        if PY_311:
-        # This can be replaced with adding the z option when we drop support for
+            value = f"{numerical_value:z.{precision}f}"
-        # Python 3.10
+        else:
-        value = NEGATIVE_ZERO_PATTERN.sub(r"\1", value)
+            value = f"{numerical_value:.{precision}f}"
+            if value.startswith("-0") and NEGATIVE_ZERO_PATTERN.match(value):
+                value = value[1:]
 
     return value

tests/components/sensor/test_init.py

@@ -17,6 +17,7 @@ from homeassistant.components.sensor import (
     SensorEntity,
     SensorEntityDescription,
     SensorStateClass,
+    async_rounded_state,
     async_update_suggested_units,
 )
 from homeassistant.config_entries import ConfigEntry, ConfigFlow
@@ -557,6 +558,22 @@ async def test_restore_sensor_restore_state(
             100,
             "38",
         ),
+        (
+            SensorDeviceClass.ATMOSPHERIC_PRESSURE,
+            UnitOfPressure.INHG,
+            UnitOfPressure.HPA,
+            UnitOfPressure.HPA,
+            -0.00,
+            "0.0",
+        ),
+        (
+            SensorDeviceClass.ATMOSPHERIC_PRESSURE,
+            UnitOfPressure.INHG,
+            UnitOfPressure.HPA,
+            UnitOfPressure.HPA,
+            -0.00001,
+            "0",
+        ),
     ],
 )
 async def test_custom_unit(
@@ -592,10 +609,15 @@ async def test_custom_unit(
     assert await async_setup_component(hass, "sensor", {"sensor": {"platform": "test"}})
     await hass.async_block_till_done()
 
-    state = hass.states.get(entity0.entity_id)
+    entity_id = entity0.entity_id
+    state = hass.states.get(entity_id)
     assert state.state == custom_state
     assert state.attributes[ATTR_UNIT_OF_MEASUREMENT] == state_unit
 
+    assert (
+        async_rounded_state(hass, entity_id, hass.states.get(entity_id)) == custom_state
+    )
+
 
 @pytest.mark.parametrize(
     (
@@ -902,7 +924,7 @@ async def test_custom_unit_change(
             "1000000",
             "1093613",
             SensorDeviceClass.DISTANCE,
-        ),
+        )
     ],
 )
 async def test_unit_conversion_priority(
@@ -1130,6 +1152,9 @@ async def test_unit_conversion_priority_precision(
         "sensor": {"suggested_display_precision": 2},
         "sensor.private": {"suggested_unit_of_measurement": automatic_unit},
     }
+    assert float(async_rounded_state(hass, entity0.entity_id, state)) == pytest.approx(
+        round(automatic_state, 2)
+    )
 
     # Unregistered entity -> Follow native unit
     state = hass.states.get(entity1.entity_id)
@@ -1172,6 +1197,20 @@ async def test_unit_conversion_priority_precision(
     assert float(state.state) == pytest.approx(custom_state)
     assert state.attributes[ATTR_UNIT_OF_MEASUREMENT] == custom_unit
 
+    # Set a display_precision, this should have priority over suggested_display_precision
+    entity_registry.async_update_entity_options(
+        entity0.entity_id,
+        "sensor",
+        {"suggested_display_precision": 2, "display_precision": 4},
+    )
+    entry0 = entity_registry.async_get(entity0.entity_id)
+    assert entry0.options["sensor"]["suggested_display_precision"] == 2
+    assert entry0.options["sensor"]["display_precision"] == 4
+    await hass.async_block_till_done()
+    assert float(async_rounded_state(hass, entity0.entity_id, state)) == pytest.approx(
+        round(custom_state, 4)
+    )
+
 
 @pytest.mark.parametrize(
     (
@@ -2362,3 +2401,39 @@ async def test_name(hass: HomeAssistant) -> None:
 
     state = hass.states.get(entity4.entity_id)
     assert state.attributes == {"device_class": "battery", "friendly_name": "Battery"}
+
+
+def test_async_rounded_state_unregistered_entity_is_passthrough(
+    hass: HomeAssistant,
+) -> None:
+    """Test async_rounded_state on unregistered entity is passthrough."""
+    hass.states.async_set("sensor.test", "1.004")
+    state = hass.states.get("sensor.test")
+    assert async_rounded_state(hass, "sensor.test", state) == "1.004"
+    hass.states.async_set("sensor.test", "-0.0")
+    state = hass.states.get("sensor.test")
+    assert async_rounded_state(hass, "sensor.test", state) == "-0.0"
+
+
+def test_async_rounded_state_registered_entity_with_display_precision(
+    hass: HomeAssistant,
+) -> None:
+    """Test async_rounded_state on registered with display precision.
+
+    The -0 should be dropped.
+    """
+    entity_registry = er.async_get(hass)
+
+    entry = entity_registry.async_get_or_create("sensor", "test", "very_unique")
+    entity_registry.async_update_entity_options(
+        entry.entity_id,
+        "sensor",
+        {"suggested_display_precision": 2, "display_precision": 4},
+    )
+    entity_id = entry.entity_id
+    hass.states.async_set(entity_id, "1.004")
+    state = hass.states.get(entity_id)
+    assert async_rounded_state(hass, entity_id, state) == "1.0040"
+    hass.states.async_set(entity_id, "-0.0")
+    state = hass.states.get(entity_id)
+    assert async_rounded_state(hass, entity_id, state) == "0.0000"

tests/helpers/test_template.py

@@ -3889,6 +3889,8 @@ def test_state_with_unit_and_rounding(hass: HomeAssistant) -> None:
 
     hass.states.async_set("sensor.test", "23", {ATTR_UNIT_OF_MEASUREMENT: "beers"})
     hass.states.async_set("sensor.test2", "23", {ATTR_UNIT_OF_MEASUREMENT: "beers"})
+    hass.states.async_set("sensor.test3", "-0.0", {ATTR_UNIT_OF_MEASUREMENT: "beers"})
+    hass.states.async_set("sensor.test4", "-0", {ATTR_UNIT_OF_MEASUREMENT: "beers"})
 
     # state_with_unit property
     tpl = template.Template("{{ states.sensor.test.state_with_unit }}", hass)
@@ -3905,6 +3907,8 @@ def test_state_with_unit_and_rounding(hass: HomeAssistant) -> None:
     # AllStates.__call__ and rounded=True
     tpl7 = template.Template("{{ states('sensor.test', rounded=True) }}", hass)
     tpl8 = template.Template("{{ states('sensor.test2', rounded=True) }}", hass)
+    tpl9 = template.Template("{{ states('sensor.test3', rounded=True) }}", hass)
+    tpl10 = template.Template("{{ states('sensor.test4', rounded=True) }}", hass)
 
     assert tpl.async_render() == "23.00 beers"
     assert tpl2.async_render() == "23 beers"
@@ -3914,6 +3918,8 @@ def test_state_with_unit_and_rounding(hass: HomeAssistant) -> None:
     assert tpl6.async_render() == "23 beers"
     assert tpl7.async_render() == 23.0
     assert tpl8.async_render() == 23
+    assert tpl9.async_render() == 0.0
+    assert tpl10.async_render() == 0
 
     hass.states.async_set("sensor.test", "23.015", {ATTR_UNIT_OF_MEASUREMENT: "beers"})
     hass.states.async_set("sensor.test2", "23.015", {ATTR_UNIT_OF_MEASUREMENT: "beers"})