Uptime sensor (#9856)

* Added uptime sensor for homeassistant

* Fixed pylint and flake8 errors

* Made requested changes from PR

- Fixed stale docstrings
- Changed default state to None
- Added ability for user to use hours or days

* Fixed typo

* Added unit_of_measurement check to test

* Converted to async

- Changed tests to work with async

* Minor updates

homeassistant/components/sensor/uptime.py

@@ -0,0 +1,78 @@
+"""
+Component to retrieve uptime for Home Assistant.
+
+For more details about this platform, please refer to the documentation at
+https://home-assistant.io/components/sensor.uptime/
+"""
+import asyncio
+import logging
+
+import voluptuous as vol
+
+import homeassistant.helpers.config_validation as cv
+import homeassistant.util.dt as dt_util
+from homeassistant.components.sensor import PLATFORM_SCHEMA
+from homeassistant.const import (
+    CONF_NAME, CONF_UNIT_OF_MEASUREMENT)
+from homeassistant.helpers.entity import Entity
+
+_LOGGER = logging.getLogger(__name__)
+
+DEFAULT_NAME = 'Uptime'
+
+PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
+    vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string,
+    vol.Optional(CONF_UNIT_OF_MEASUREMENT, default='days'):
+        vol.All(cv.string, vol.In(['hours', 'days']))
+})
+
+
+@asyncio.coroutine
+def async_setup_platform(hass, config, async_add_devices, discovery_info=None):
+    """Set up the uptime sensor platform."""
+    name = config.get(CONF_NAME)
+    units = config.get(CONF_UNIT_OF_MEASUREMENT)
+    async_add_devices([UptimeSensor(name, units)], True)
+
+
+class UptimeSensor(Entity):
+    """Representation of an uptime sensor."""
+
+    def __init__(self, name, units):
+        """Initialize the uptime sensor."""
+        self._name = name
+        self._icon = 'mdi:clock'
+        self._units = units
+        self.initial = dt_util.now()
+        self._state = None
+
+    @property
+    def name(self):
+        """Return the name of the sensor."""
+        return self._name
+
+    @property
+    def icon(self):
+        """Icon to display in the front end."""
+        return self._icon
+
+    @property
+    def unit_of_measurement(self):
+        """Return the unit of measurement the value is expressed in."""
+        return self._units
+
+    @property
+    def state(self):
+        """Return the state of the sensor."""
+        return self._state
+
+    @asyncio.coroutine
+    def async_update(self):
+        """Update the state of the sensor."""
+        delta = dt_util.now() - self.initial
+        div_factor = 3600
+        if self.unit_of_measurement == 'days':
+            div_factor *= 24
+        delta = delta.total_seconds() / div_factor
+        self._state = round(delta, 2)
+        _LOGGER.debug("New value: %s", delta)

tests/components/sensor/test_uptime.py

@@ -0,0 +1,88 @@
+"""The tests for the uptime sensor platform."""
+import unittest
+from unittest.mock import patch
+from datetime import timedelta
+
+from homeassistant.util.async import run_coroutine_threadsafe
+from homeassistant.setup import setup_component
+from homeassistant.components.sensor.uptime import UptimeSensor
+from tests.common import get_test_home_assistant
+
+
+class TestUptimeSensor(unittest.TestCase):
+    """Test the uptime sensor."""
+
+    def setUp(self):
+        """Set up things to run when tests begin."""
+        self.hass = get_test_home_assistant()
+
+    def tearDown(self):
+        """Stop everything that was started."""
+        self.hass.stop()
+
+    def test_uptime_min_config(self):
+        """Test minimum uptime configutation."""
+        config = {
+            'sensor': {
+                'platform': 'uptime',
+            }
+        }
+        assert setup_component(self.hass, 'sensor', config)
+
+    def test_uptime_sensor_name_change(self):
+        """Test uptime sensor with different name."""
+        config = {
+            'sensor': {
+                'platform': 'uptime',
+                'name': 'foobar',
+            }
+        }
+        assert setup_component(self.hass, 'sensor', config)
+
+    def test_uptime_sensor_config_hours(self):
+        """Test uptime sensor with hours defined in config."""
+        config = {
+            'sensor': {
+                'platform': 'uptime',
+                'unit_of_measurement': 'hours',
+            }
+        }
+        assert setup_component(self.hass, 'sensor', config)
+
+    def test_uptime_sensor_days_output(self):
+        """Test uptime sensor output data."""
+        sensor = UptimeSensor('test', 'days')
+        self.assertEqual(sensor.unit_of_measurement, 'days')
+        new_time = sensor.initial + timedelta(days=1)
+        with patch('homeassistant.util.dt.now', return_value=new_time):
+            run_coroutine_threadsafe(
+                sensor.async_update(),
+                self.hass.loop
+            ).result()
+            self.assertEqual(sensor.state, 1.00)
+        new_time = sensor.initial + timedelta(days=111.499)
+        with patch('homeassistant.util.dt.now', return_value=new_time):
+            run_coroutine_threadsafe(
+                sensor.async_update(),
+                self.hass.loop
+            ).result()
+            self.assertEqual(sensor.state, 111.50)
+
+    def test_uptime_sensor_hours_output(self):
+        """Test uptime sensor output data."""
+        sensor = UptimeSensor('test', 'hours')
+        self.assertEqual(sensor.unit_of_measurement, 'hours')
+        new_time = sensor.initial + timedelta(hours=16)
+        with patch('homeassistant.util.dt.now', return_value=new_time):
+            run_coroutine_threadsafe(
+                sensor.async_update(),
+                self.hass.loop
+            ).result()
+            self.assertEqual(sensor.state, 16.00)
+        new_time = sensor.initial + timedelta(hours=72.499)
+        with patch('homeassistant.util.dt.now', return_value=new_time):
+            run_coroutine_threadsafe(
+                sensor.async_update(),
+                self.hass.loop
+            ).result()
+            self.assertEqual(sensor.state, 72.50)