Fix number rounding for protobuf messages (#93)

* Fix number rounding for protobuf messages

* Switch to converter_field

aioesphomeapi/model.py

@@ -14,6 +14,8 @@ from typing import (
     cast,
 )
 
+from .util import fix_float_single_double_conversion
+
 if TYPE_CHECKING:
     from .api_pb2 import HomeassistantServiceMap  # type: ignore
 
@@ -407,9 +409,15 @@ class ClimateInfo(EntityInfo):
     supported_modes: List[ClimateMode] = converter_field(
         default_factory=list, converter=ClimateMode.convert_list
     )
-    visual_min_temperature: float = 0.0
-    visual_max_temperature: float = 0.0
-    visual_temperature_step: float = 0.0
+    visual_min_temperature: float = converter_field(
+        default=0.0, converter=fix_float_single_double_conversion
+    )
+    visual_max_temperature: float = converter_field(
+        default=0.0, converter=fix_float_single_double_conversion
+    )
+    visual_temperature_step: float = converter_field(
+        default=0.0, converter=fix_float_single_double_conversion
+    )
     legacy_supports_away: bool = False
     supports_action: bool = False
     supported_fan_modes: List[ClimateFanMode] = converter_field(
@@ -446,10 +454,18 @@ class ClimateState(EntityState):
     action: Optional[ClimateAction] = converter_field(
         default=ClimateAction.OFF, converter=ClimateAction.convert
     )
-    current_temperature: float = 0.0
-    target_temperature: float = 0.0
-    target_temperature_low: float = 0.0
-    target_temperature_high: float = 0.0
+    current_temperature: float = converter_field(
+        default=0.0, converter=fix_float_single_double_conversion
+    )
+    target_temperature: float = converter_field(
+        default=0.0, converter=fix_float_single_double_conversion
+    )
+    target_temperature_low: float = converter_field(
+        default=0.0, converter=fix_float_single_double_conversion
+    )
+    target_temperature_high: float = converter_field(
+        default=0.0, converter=fix_float_single_double_conversion
+    )
     legacy_away: bool = False
     fan_mode: Optional[ClimateFanMode] = converter_field(
         default=ClimateFanMode.ON, converter=ClimateFanMode.convert
@@ -475,12 +491,16 @@ class NumberInfo(EntityInfo):
     icon: str = ""
     min_value: float = 0.0
     max_value: float = 0.0
-    step: float = 0.0
+    step: float = converter_field(
+        default=0.0, converter=fix_float_single_double_conversion
+    )
 
 
 @dataclass(frozen=True)
 class NumberState(EntityState):
-    state: float = 0.0
+    state: float = converter_field(
+        default=0.0, converter=fix_float_single_double_conversion
+    )
     missing_state: bool = False
 
 

aioesphomeapi/util.py

@@ -1,3 +1,4 @@
+import math
 from typing import Optional
 
 
@@ -26,3 +27,26 @@ def bytes_to_varuint(value: bytes) -> Optional[int]:
         if (val & 0x80) == 0:
             return result
     return None
+
+
+def fix_float_single_double_conversion(value: float) -> float:
+    """Fix precision for single-precision floats and return what was probably
+    meant as a float.
+
+    In ESPHome we work with single-precision floats internally for performance.
+    But python uses double-precision floats, and when protobuf reads the message
+    it's auto-converted to a double (which is possible losslessly).
+
+    Unfortunately the float representation of 0.1 converted to a double is not the
+    double representation of 0.1, but 0.10000000149011612.
+
+    This methods tries to round to the closest decimal value that a float of this
+    magnitude can accurately represent.
+    """
+    if value == 0 or not math.isfinite(value):
+        return value
+    abs_val = abs(value)
+    # assume ~7 decimals of precision for floats to be safe
+    l10 = math.ceil(math.log10(abs_val))
+    prec = 7 - l10
+    return round(value, prec)

tests/test_util.py

@@ -1,3 +1,5 @@
+import math
+
 import pytest
 
 from aioesphomeapi import util
@@ -20,3 +22,29 @@ def test_varuint_to_bytes(val, encoded):
 @pytest.mark.parametrize("val, encoded", VARUINT_TESTCASES)
 def test_bytes_to_varuint(val, encoded):
     assert util.bytes_to_varuint(encoded) == val
+
+
+@pytest.mark.parametrize(
+    "input, output",
+    [
+        (0, 0),
+        (float("inf"), float("inf")),
+        (float("-inf"), float("-inf")),
+        (0.1, 0.1),
+        (-0.0, -0.0),
+        (0.10000000149011612, 0.1),
+        (1, 1),
+        (-1, -1),
+        (-0.10000000149011612, -0.1),
+        (-152198557936981706463557226105667584, -152198600000000000000000000000000000),
+        (-0.0030539485160261, -0.003053949),
+        (0.5, 0.5),
+        (0.0000000000000019, 0.0000000000000019),
+    ],
+)
+def test_fix_float_single_double_conversion(input, output):
+    assert util.fix_float_single_double_conversion(input) == output
+
+
+def test_fix_float_single_double_conversion_nan():
+    assert math.isnan(util.fix_float_single_double_conversion(float("nan")))