Restore target temperature for generic thermostat (#10635)

* Restore target temp for generic thermostat

* Fix lint

homeassistant/components/climate/generic_thermostat.py

@@ -21,6 +21,7 @@ from homeassistant.helpers import condition
 from homeassistant.helpers.event import (
     async_track_state_change, async_track_time_interval)
 import homeassistant.helpers.config_validation as cv
+from homeassistant.helpers.restore_state import async_get_last_state
 
 _LOGGER = logging.getLogger(__name__)
 
@@ -117,6 +118,17 @@ class GenericThermostat(ClimateDevice):
         if sensor_state:
             self._async_update_temp(sensor_state)
 
+    @asyncio.coroutine
+    def async_added_to_hass(self):
+        """Run when entity about to be added."""
+        # If we have an old state and no target temp, restore
+        if self._target_temp is None:
+            old_state = yield from async_get_last_state(self.hass,
+                                                        self.entity_id)
+            if old_state is not None:
+                self._target_temp = float(
+                    old_state.attributes[ATTR_TEMPERATURE])
+
     @property
     def should_poll(self):
         """Return the polling state."""

tests/components/climate/test_generic_thermostat.py

@@ -6,7 +6,7 @@ from unittest import mock
 import pytz
 
 import homeassistant.core as ha
-from homeassistant.core import callback
+from homeassistant.core import callback, CoreState, State
 from homeassistant.setup import setup_component, async_setup_component
 from homeassistant.const import (
     ATTR_UNIT_OF_MEASUREMENT,
@@ -15,13 +15,15 @@ from homeassistant.const import (
     STATE_ON,
     STATE_OFF,
     TEMP_CELSIUS,
+    ATTR_TEMPERATURE
 )
 from homeassistant import loader
 from homeassistant.util.unit_system import METRIC_SYSTEM
 from homeassistant.util.async import run_coroutine_threadsafe
 from homeassistant.components import climate, input_boolean, switch
 import homeassistant.components as comps
-from tests.common import assert_setup_component, get_test_home_assistant
+from tests.common import (assert_setup_component, get_test_home_assistant,
+                          mock_restore_cache)
 
 
 ENTITY = 'climate.test'
@@ -892,3 +894,24 @@ def test_custom_setup_params(hass):
     assert state.attributes.get('min_temp') == MIN_TEMP
     assert state.attributes.get('max_temp') == MAX_TEMP
     assert state.attributes.get('temperature') == TARGET_TEMP
+
+
+@asyncio.coroutine
+def test_restore_state(hass):
+    """Ensure states are restored on startup."""
+    mock_restore_cache(hass, (
+        State('climate.test_thermostat', '0', {ATTR_TEMPERATURE: "20"}),
+    ))
+
+    hass.state = CoreState.starting
+
+    yield from async_setup_component(
+        hass, climate.DOMAIN, {'climate': {
+            'platform': 'generic_thermostat',
+            'name': 'test_thermostat',
+            'heater': ENT_SWITCH,
+            'target_sensor': ENT_SENSOR,
+        }})
+
+    state = hass.states.get('climate.test_thermostat')
+    assert(state.attributes[ATTR_TEMPERATURE] == 20)