Merge pull request #948 from balloob/sensor_template

First draft of sensor.template.

homeassistant/components/sensor/template.py

@@ -0,0 +1,113 @@
+"""
+homeassistant.components.sensor.template
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Allows the creation of a sensor that breaks out state_attributes
+from other entities.
+
+For more details about this platform, please refer to the documentation at
+https://home-assistant.io/components/sensor.template/
+"""
+import logging
+
+from homeassistant.helpers.entity import Entity
+from homeassistant.core import EVENT_STATE_CHANGED
+from homeassistant.const import (
+    ATTR_FRIENDLY_NAME,
+    CONF_VALUE_TEMPLATE,
+    ATTR_UNIT_OF_MEASUREMENT)
+
+from homeassistant.util import template
+from homeassistant.exceptions import TemplateError
+
+_LOGGER = logging.getLogger(__name__)
+
+CONF_SENSORS = 'sensors'
+
+STATE_ERROR = 'error'
+
+
+# pylint: disable=unused-argument
+def setup_platform(hass, config, add_devices, discovery_info=None):
+    """ Sets up the sensors. """
+
+    sensors = []
+    if config.get(CONF_SENSORS) is None:
+        _LOGGER.error("Missing configuration data for sensor platfoprm")
+        return False
+
+    for device, device_config in config[CONF_SENSORS].items():
+        if not isinstance(device_config, dict):
+            _LOGGER.error("Missing configuration data for sensor %s", device)
+            continue
+        friendly_name = device_config.get(ATTR_FRIENDLY_NAME, device)
+        unit_of_measurement = device_config.get(ATTR_UNIT_OF_MEASUREMENT)
+        state_template = device_config.get(CONF_VALUE_TEMPLATE)
+        if state_template is None:
+            _LOGGER.error(
+                "Missing %s for sensor %s", CONF_VALUE_TEMPLATE, device)
+            continue
+        sensors.append(
+            SensorTemplate(
+                hass,
+                friendly_name,
+                unit_of_measurement,
+                state_template)
+            )
+    if sensors is None:
+        _LOGGER.error("No sensors added.")
+        return False
+    add_devices(sensors)
+    return True
+
+
+class SensorTemplate(Entity):
+    """ Represents a Template Sensor. """
+
+    # pylint: disable=too-many-arguments
+    def __init__(self,
+                 hass,
+                 friendly_name,
+                 unit_of_measurement,
+                 state_template):
+
+        self.hass = hass
+        self._name = friendly_name
+        self._unit_of_measurement = unit_of_measurement
+        self._template = state_template
+        self.update()
+
+        def _update_callback(_event):
+            """ Called when the target device changes state. """
+            # This can be called before the entity is properly
+            # initialised, so check before updating state,
+            if self.entity_id:
+                self.update_ha_state(True)
+
+        self.hass.bus.listen(EVENT_STATE_CHANGED, _update_callback)
+
+    @property
+    def name(self):
+        """ Returns the name of the device. """
+        return self._name
+
+    @property
+    def state(self):
+        """ Returns the state of the device. """
+        return self._state
+
+    @property
+    def unit_of_measurement(self):
+        """ Returns the unit_of_measurement of the device. """
+        return self._unit_of_measurement
+
+    @property
+    def should_poll(self):
+        """ Tells Home Assistant not to poll this entity. """
+        return False
+
+    def update(self):
+        try:
+            self._state = template.render(self.hass, self._template)
+        except TemplateError as ex:
+            self._state = STATE_ERROR
+            _LOGGER.error(ex)

tests/components/sensor/test_template.py

@@ -0,0 +1,63 @@
+"""
+tests.components.sensor.template
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Tests template sensor.
+"""
+from unittest.mock import patch
+
+import pytest
+
+import homeassistant.core as ha
+import homeassistant.components.sensor as sensor
+
+
+class TestTemplateSensor:
+    """ Test the Template sensor. """
+
+    def setup_method(self, method):
+        self.hass = ha.HomeAssistant()
+
+    def teardown_method(self, method):
+        """ Stop down stuff we started. """
+        self.hass.stop()
+
+    def test_template(self):
+        assert sensor.setup(self.hass, {
+            'sensor': {
+                'platform': 'template',
+                'sensors': {
+                    'test_template_sensor': {
+                        'value_template':
+                            "{{ states.sensor.test_state.state }}"
+                    }
+                }
+            }
+        })
+
+        state = self.hass.states.get('sensor.test_template_sensor')
+        assert state.state == ''
+
+        self.hass.states.set('sensor.test_state', 'Works')
+        self.hass.pool.block_till_done()
+        state = self.hass.states.get('sensor.test_template_sensor')
+        assert state.state == 'Works'
+
+    def test_template_syntax_error(self):
+        assert sensor.setup(self.hass, {
+            'sensor': {
+                'platform': 'template',
+                'sensors': {
+                    'test_template_sensor': {
+                        'value_template':
+                            "{% if rubbish %}"
+                    }
+                }
+            }
+        })
+
+
+        self.hass.states.set('sensor.test_state', 'Works')
+        self.hass.pool.block_till_done()
+        state = self.hass.states.get('sensor.test_template_sensor')
+        assert state.state == 'error'