Have statemachine.track_change work on new states

homeassistant/__init__.py

@@ -614,13 +614,19 @@ class StateMachine(object):
         @ft.wraps(action)
         def state_listener(event):
             """ The listener that listens for specific state changes. """
-            if event.data['entity_id'] in entity_ids and \
-                    'old_state' in event.data and \
-                    _matcher(event.data['old_state'].state, from_state) and \
-                    _matcher(event.data['new_state'].state, to_state):
+            if event.data['entity_id'] not in entity_ids:
+                return
+
+            if 'old_state' in event.data:
+                old_state = event.data['old_state'].state
+            else:
+                old_state = None
+
+            if _matcher(old_state, from_state) and \
+               _matcher(event.data['new_state'].state, to_state):
 
                 action(event.data['entity_id'],
-                       event.data['old_state'],
+                       event.data.get('old_state'),
                        event.data['new_state'])
 
         self._bus.listen(EVENT_STATE_CHANGED, state_listener)

tests/test_component_group.py

@@ -146,6 +146,32 @@ class TestComponentsGroup(unittest.TestCase):
         # Test with non-group state
         self.assertEqual([], group.get_entity_ids(self.hass, 'switch.AC'))
 
+    def test_group_being_init_before_first_tracked_state_is_set_to_on(self):
+        """ Test if the group turns on if no states existed and now a state it is
+            tracking is being added as ON. """
+        test_group = group.Group(
+            self.hass, 'test group', ['light.not_there_1'])
+
+        self.hass.states.set('light.not_there_1', STATE_ON)
+
+        self.hass.pool.block_till_done()
+
+        group_state = self.hass.states.get(test_group.entity_id)
+        self.assertEqual(STATE_ON, group_state.state)
+
+    def test_group_being_init_before_first_tracked_state_is_set_to_off(self):
+        """ Test if the group turns off if no states existed and now a state it is
+            tracking is being added as OFF. """
+        test_group = group.Group(
+            self.hass, 'test group', ['light.not_there_1'])
+
+        self.hass.states.set('light.not_there_1', STATE_OFF)
+
+        self.hass.pool.block_till_done()
+
+        group_state = self.hass.states.get(test_group.entity_id)
+        self.assertEqual(STATE_OFF, group_state.state)
+
     def test_setup(self):
         """ Test setup method. """
         self.assertTrue(