Embed all platforms into components (#20677)

* Consolidate all components with platforms

* Organize tests

* Fix more tests

* Fix Verisure tests

* one final test fix

* Add change

* Fix coverage

homeassistant/components/alarmdecoder/sensor.py

@@ -0,0 +1,64 @@
+"""
+Support for AlarmDecoder Sensors (Shows Panel Display).
+
+For more details about this platform, please refer to the documentation at
+https://home-assistant.io/components/sensor.alarmdecoder/
+"""
+import logging
+
+from homeassistant.helpers.entity import Entity
+from homeassistant.components.alarmdecoder import (SIGNAL_PANEL_MESSAGE)
+
+_LOGGER = logging.getLogger(__name__)
+
+DEPENDENCIES = ['alarmdecoder']
+
+
+def setup_platform(hass, config, add_entities, discovery_info=None):
+    """Set up for AlarmDecoder sensor devices."""
+    _LOGGER.debug("AlarmDecoderSensor: setup_platform")
+
+    device = AlarmDecoderSensor(hass)
+
+    add_entities([device])
+
+
+class AlarmDecoderSensor(Entity):
+    """Representation of an AlarmDecoder keypad."""
+
+    def __init__(self, hass):
+        """Initialize the alarm panel."""
+        self._display = ""
+        self._state = None
+        self._icon = 'mdi:alarm-check'
+        self._name = 'Alarm Panel Display'
+
+    async def async_added_to_hass(self):
+        """Register callbacks."""
+        self.hass.helpers.dispatcher.async_dispatcher_connect(
+            SIGNAL_PANEL_MESSAGE, self._message_callback)
+
+    def _message_callback(self, message):
+        if self._display != message.text:
+            self._display = message.text
+            self.schedule_update_ha_state()
+
+    @property
+    def icon(self):
+        """Return the icon if any."""
+        return self._icon
+
+    @property
+    def state(self):
+        """Return the overall state."""
+        return self._display
+
+    @property
+    def name(self):
+        """Return the name of the device."""
+        return self._name
+
+    @property
+    def should_poll(self):
+        """No polling needed."""
+        return False