diff --git a/homeassistant/components/__init__.py b/homeassistant/components/__init__.py
index 3cb5f49939b..73fb18f1537 100644
--- a/homeassistant/components/__init__.py
+++ b/homeassistant/components/__init__.py
@@ -59,7 +59,7 @@ def is_on(hass, entity_id=None):
     if entity_id:
         group = get_component('group')
 
-        entity_ids = group.expand_entity_ids([entity_id])
+        entity_ids = group.expand_entity_ids(hass, [entity_id])
     else:
         entity_ids = hass.states.entity_ids
 
@@ -80,13 +80,19 @@ def is_on(hass, entity_id=None):
     return False
 
 
-def turn_on(hass, **service_data):
+def turn_on(hass, entity_id=None, **service_data):
     """ Turns specified entity on if possible. """
+    if entity_id is not None:
+        service_data[ATTR_ENTITY_ID] = entity_id
+
     hass.call_service(ha.DOMAIN, SERVICE_TURN_ON, service_data)
 
 
-def turn_off(hass, **service_data):
+def turn_off(hass, entity_id=None, **service_data):
     """ Turns specified entity off. """
+    if entity_id is not None:
+        service_data[ATTR_ENTITY_ID] = entity_id
+
     hass.call_service(ha.DOMAIN, SERVICE_TURN_OFF, service_data)
 
 
@@ -169,7 +175,6 @@ def setup(hass, config):
 
     def handle_turn_service(service):
         """ Method to handle calls to homeassistant.turn_on/off. """
-
         entity_ids = extract_entity_ids(hass, service)
 
         # Generic turn on/off method requires entity id
diff --git a/homeassistant/test.py b/homeassistant/test.py
index c141a6a9946..e960596a58d 100644
--- a/homeassistant/test.py
+++ b/homeassistant/test.py
@@ -20,6 +20,7 @@ import homeassistant as ha
 import homeassistant.loader as loader
 import homeassistant.util as util
 import homeassistant.remote as remote
+import homeassistant.components as comps
 import homeassistant.components.http as http
 
 API_PASSWORD = "test1234"
@@ -456,6 +457,63 @@ class TestUtil(unittest.TestCase):
             util.ensure_unique_string("Beer", ["Beer", "Beer_2"]))
 
 
+class TestComponentsCore(unittest.TestCase):
+    """ Tests homeassistant.components module. """
+
+    def setUp(self):  # pylint: disable=invalid-name
+        """ Init needed objects. """
+        self.hass = ha.HomeAssistant()
+        loader.prepare(self.hass)
+        self.assertTrue(comps.setup(self.hass, {}))
+
+        self.hass.states.set('light.Bowl', comps.STATE_ON)
+        self.hass.states.set('light.Ceiling', comps.STATE_OFF)
+
+    def test_is_on(self):
+        """ Test is_on method. """
+        self.assertTrue(comps.is_on(self.hass, 'light.Bowl'))
+        self.assertFalse(comps.is_on(self.hass, 'light.Ceiling'))
+        self.assertTrue(comps.is_on(self.hass))
+
+    def test_turn_on(self):
+        """ Test turn_on method. """
+        runs = []
+        self.hass.services.register(
+            'light', comps.SERVICE_TURN_ON, lambda x: runs.append(1))
+
+        comps.turn_on(self.hass, 'light.Ceiling')
+
+        self.hass._pool.block_till_done()
+
+        self.assertEqual(1, len(runs))
+
+    def test_turn_off(self):
+        """ Test turn_off method. """
+        runs = []
+        self.hass.services.register(
+            'light', comps.SERVICE_TURN_OFF, lambda x: runs.append(1))
+
+        comps.turn_off(self.hass, 'light.Bowl')
+
+        self.hass._pool.block_till_done()
+
+        self.assertEqual(1, len(runs))
+
+    def test_extract_entity_ids(self):
+        """ Test extract_entity_ids method. """
+        call = ha.ServiceCall('light', 'turn_on',
+                              {comps.ATTR_ENTITY_ID: 'light.Bowl'})
+
+        self.assertEqual(['light.Bowl'],
+                         comps.extract_entity_ids(self.hass, call))
+
+        call = ha.ServiceCall('light', 'turn_on',
+                              {comps.ATTR_ENTITY_ID: ['light.Bowl']})
+
+        self.assertEqual(['light.Bowl'],
+                         comps.extract_entity_ids(self.hass, call))
+
+
 class TestHTTP(unittest.TestCase):
     """ Test the HTTP debug interface and API. """