Improve typing of trend component (#99719)

* Some typing in trend component

* Add missing type hint

* Enable strict typing on trend

.strict-typing

@@ -336,6 +336,7 @@ homeassistant.components.trafikverket_camera.*
 homeassistant.components.trafikverket_ferry.*
 homeassistant.components.trafikverket_train.*
 homeassistant.components.trafikverket_weatherstation.*
+homeassistant.components.trend.*
 homeassistant.components.tts.*
 homeassistant.components.twentemilieu.*
 homeassistant.components.unifi.*

homeassistant/components/trend/binary_sensor.py

@@ -2,8 +2,10 @@
 from __future__ import annotations
 
 from collections import deque
+from collections.abc import Mapping
 import logging
 import math
+from typing import Any
 
 import numpy as np
 import voluptuous as vol
@@ -12,6 +14,7 @@ from homeassistant.components.binary_sensor import (
     DEVICE_CLASSES_SCHEMA,
     ENTITY_ID_FORMAT,
     PLATFORM_SCHEMA,
+    BinarySensorDeviceClass,
     BinarySensorEntity,
 )
 from homeassistant.const import (
@@ -117,20 +120,22 @@ class SensorTrend(BinarySensorEntity):
     """Representation of a trend Sensor."""
 
     _attr_should_poll = False
+    _gradient = 0.0
+    _state: bool | None = None
 
     def __init__(
         self,
-        hass,
-        device_id,
-        friendly_name,
-        entity_id,
-        attribute,
-        device_class,
-        invert,
-        max_samples,
-        min_gradient,
-        sample_duration,
-    ):
+        hass: HomeAssistant,
+        device_id: str,
+        friendly_name: str,
+        entity_id: str,
+        attribute: str,
+        device_class: BinarySensorDeviceClass,
+        invert: bool,
+        max_samples: int,
+        min_gradient: float,
+        sample_duration: int,
+    ) -> None:
         """Initialize the sensor."""
         self._hass = hass
         self.entity_id = generate_entity_id(ENTITY_ID_FORMAT, device_id, hass=hass)
@@ -141,17 +146,15 @@ class SensorTrend(BinarySensorEntity):
         self._invert = invert
         self._sample_duration = sample_duration
         self._min_gradient = min_gradient
-        self._gradient = None
-        self._state = None
-        self.samples = deque(maxlen=max_samples)
+        self.samples: deque = deque(maxlen=max_samples)
 
     @property
-    def is_on(self):
+    def is_on(self) -> bool | None:
         """Return true if sensor is on."""
         return self._state
 
     @property
-    def extra_state_attributes(self):
+    def extra_state_attributes(self) -> Mapping[str, Any]:
         """Return the state attributes of the sensor."""
         return {
             ATTR_ENTITY_ID: self._entity_id,
@@ -214,7 +217,7 @@ class SensorTrend(BinarySensorEntity):
         if self._invert:
             self._state = not self._state
 
-    def _calculate_gradient(self):
+    def _calculate_gradient(self) -> None:
         """Compute the linear trend gradient of the current samples.
 
         This need run inside executor.

mypy.ini

@@ -3123,6 +3123,16 @@ disallow_untyped_defs = true
 warn_return_any = true
 warn_unreachable = true
 
+[mypy-homeassistant.components.trend.*]
+check_untyped_defs = true
+disallow_incomplete_defs = true
+disallow_subclassing_any = true
+disallow_untyped_calls = true
+disallow_untyped_decorators = true
+disallow_untyped_defs = true
+warn_return_any = true
+warn_unreachable = true
+
 [mypy-homeassistant.components.tts.*]
 check_untyped_defs = true
 disallow_incomplete_defs = true