Prevent devices from being discovered twice

homeassistant/components/chromecast.py

@@ -113,6 +113,11 @@ def media_prev_track(hass, entity_id=None):
 
 def setup_chromecast(casts, host):
     """ Tries to convert host to Chromecast object and set it up. """
+
+    # Check if already setup
+    if any(cast.host == host for cast in casts.values()):
+        return
+
     try:
         cast = pychromecast.PyChromecast(host)
 

homeassistant/components/light/hue.py

@@ -81,6 +81,12 @@ class HueLight(ToggleDevice):
         """ Get the mame of the Hue light. """
         return self.info['name']
 
+    @property
+    def unique_id(self):
+        """ Returns the id of this Hue light """
+        return "{}.{}".format(
+            self.__class__, self.info.get('uniqueid', self.get_name()))
+
     def turn_on(self, **kwargs):
         """ Turn the specified or all lights on. """
         command = {'on': True}

homeassistant/components/switch/__init__.py

@@ -86,7 +86,7 @@ def setup(hass, config):
 
         switch = platform.device_discovered(hass, config, info)
 
-        if switch is not None:
+        if switch is not None and switch not in switches.values():
             switch.entity_id = util.ensure_unique_string(
                 ENTITY_ID_FORMAT.format(util.slugify(switch.get_name())),
                 switches.keys())

homeassistant/components/switch/wemo.py

@@ -59,6 +59,11 @@ class WemoSwitch(ToggleDevice):
     def __init__(self, wemo):
         self.wemo = wemo
 
+    @property
+    def unique_id(self):
+        """ Returns the id of this WeMo switch """
+        return "{}.{}".format(self.__class__, self.wemo.serialnumber)
+
     def get_name(self):
         """ Returns the name of the switch if any. """
         return self.wemo.name

homeassistant/helpers.py

@@ -146,9 +146,6 @@ def platform_devices_from_config(config, domain, hass,
 
             devices.extend(p_devices)
 
-    if len(devices) == 0:
-        logger.error("No devices found for %s", domain)
-
     # Setup entity IDs for each device
     no_name_count = 1
 
@@ -177,6 +174,11 @@ class Device(object):
 
     entity_id = None
 
+    @property
+    def unique_id(self):
+        """ Returns a unique id. """
+        return "{}.{}".format(self.__class__, id(self))
+
     def get_name(self):
         """ Returns the name of the device if any. """
         return "No Name"
@@ -208,6 +210,10 @@ class Device(object):
         return hass.states.set(self.entity_id, self.get_state(),
                                self.get_state_attributes())
 
+    def __eq__(self, other):
+        return (isinstance(other, Device) and
+                other.unique_id == self.unique_id)
+
 
 class ToggleDevice(Device):
     """ ABC for devices that can be turned on and off. """