From e6e748ae0abe4fbad7430883b4c5fdc30a6ba555 Mon Sep 17 00:00:00 2001
From: Sean Chen <kamiyo@gmail.com>
Date: Fri, 19 Jul 2024 12:50:38 -0500
Subject: [PATCH] Add timestamp sensor for observation (#121752)

---
 homeassistant/components/nws/sensor.py | 11 ++++++++++-
 tests/components/nws/const.py          |  2 ++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/homeassistant/components/nws/sensor.py b/homeassistant/components/nws/sensor.py
index 872e1588244..d1992056d47 100644
--- a/homeassistant/components/nws/sensor.py
+++ b/homeassistant/components/nws/sensor.py
@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 from dataclasses import dataclass
+from datetime import datetime
 from types import MappingProxyType
 from typing import Any
 
@@ -28,6 +29,7 @@ from homeassistant.helpers.update_coordinator import (
     CoordinatorEntity,
     TimestampDataUpdateCoordinator,
 )
+from homeassistant.util.dt import parse_datetime
 from homeassistant.util.unit_conversion import (
     DistanceConverter,
     PressureConverter,
@@ -137,6 +139,11 @@ SENSOR_TYPES: tuple[NWSSensorEntityDescription, ...] = (
         native_unit_of_measurement=UnitOfLength.METERS,
         unit_convert=UnitOfLength.MILES,
     ),
+    NWSSensorEntityDescription(
+        key="timestamp",
+        name="Latest Observation Time",
+        device_class=SensorDeviceClass.TIMESTAMP,
+    ),
 )
 
 
@@ -190,7 +197,7 @@ class NWSSensor(CoordinatorEntity[TimestampDataUpdateCoordinator[None]], SensorE
         )
 
     @property
-    def native_value(self) -> float | None:
+    def native_value(self) -> float | datetime | None:
         """Return the state."""
         if (
             not (observation := self._nws.observation)
@@ -223,4 +230,6 @@ class NWSSensor(CoordinatorEntity[TimestampDataUpdateCoordinator[None]], SensorE
             return round(value, 1)
         if unit_of_measurement == PERCENTAGE:
             return round(value)
+        if self.device_class == SensorDeviceClass.TIMESTAMP:
+            return parse_datetime(value)
         return value
diff --git a/tests/components/nws/const.py b/tests/components/nws/const.py
index 06aef2c8da7..39e954af15a 100644
--- a/tests/components/nws/const.py
+++ b/tests/components/nws/const.py
@@ -66,6 +66,7 @@ CLEAR_NIGHT_OBSERVATION = DEFAULT_OBSERVATION.copy()
 CLEAR_NIGHT_OBSERVATION["iconTime"] = "night"
 
 SENSOR_EXPECTED_OBSERVATION_METRIC = {
+    "timestamp": "2019-08-12T23:53:00+00:00",
     "dewpoint": "5",
     "temperature": "10",
     "windChill": "5",
@@ -80,6 +81,7 @@ SENSOR_EXPECTED_OBSERVATION_METRIC = {
 }
 
 SENSOR_EXPECTED_OBSERVATION_IMPERIAL = {
+    "timestamp": "2019-08-12T23:53:00+00:00",
     "dewpoint": str(
         round(
             TemperatureConverter.convert(