[combination] Use cv.rename_key for the deprecated coeffecient key (#20159)

Co-authored-by: J. Nick Koston <nick@koston.org>

esphome/components/combination/sensor.py

@@ -1,5 +1,3 @@
-import logging
-
 import esphome.codegen as cg
 from esphome.components import sensor
 import esphome.config_validation as cv
@@ -18,8 +16,6 @@ from esphome.const import (
 from esphome.core.entity_helpers import inherit_property_from
 from esphome.types import ConfigType
 
-_LOGGER = logging.getLogger(__name__)
-
 CODEOWNERS = ["@Cat-Ion", "@kahrendt"]
 
 combination_ns = cg.esphome_ns.namespace("combination")
@@ -75,33 +71,19 @@ KALMAN_SOURCE_SCHEMA = cv.Schema(
 )
 
 
-def _migrate_coeffecient(config: ConfigType) -> ConfigType:
-    """Migrate deprecated 'coeffecient' spelling to 'coefficient'."""
-    if CONF_COEFFECIENT in config:
-        if CONF_COEFFICIENT in config:
-            raise cv.Invalid(
-                f"Cannot specify both '{CONF_COEFFICIENT}' and '{CONF_COEFFECIENT}'"
-            )
-        _LOGGER.warning(
-            "'%s' is deprecated, use '%s' instead. Will be removed in 2026.12.0",
-            CONF_COEFFECIENT,
-            CONF_COEFFICIENT,
-        )
-        config[CONF_COEFFICIENT] = config.pop(CONF_COEFFECIENT)
-    elif CONF_COEFFICIENT not in config:
-        raise cv.Invalid(f"'{CONF_COEFFICIENT}' is a required option")
-    return config
-
-
 LINEAR_SOURCE_SCHEMA = cv.All(
+    cv.rename_key(
+        CONF_COEFFECIENT,
+        CONF_COEFFICIENT,
+        removed_in="2026.12.0",
+        component="combination",
+    ),
     cv.Schema(
         {
             cv.Required(CONF_SOURCE): cv.use_id(sensor.Sensor),
-            cv.Optional(CONF_COEFFICIENT): cv.templatable(cv.float_),
-            cv.Optional(CONF_COEFFECIENT): cv.templatable(cv.float_),
+            cv.Required(CONF_COEFFICIENT): cv.templatable(cv.float_),
         }
     ),
-    _migrate_coeffecient,
 )
 
 SENSOR_ONLY_SOURCE_SCHEMA = cv.Schema(

tests/components/combination/validate-deprecated.esp32-idf.yaml

@@ -0,0 +1,15 @@
+sensor:
+  - platform: template
+    id: template_temperature1
+    lambda: return 0.6;
+  - platform: template
+    id: template_temperature2
+    lambda: return 0.8;
+  - platform: combination
+    type: linear
+    name: Linearly combined temperatures
+    sources:
+      - source: template_temperature1
+        coeffecient: 0.5
+      - source: template_temperature2
+        coefficient: 1.5