Consolidate all platforms that have no tests (#22096)

* Consolidate

* Fix tests

* Update imports

* Fix import

* Use importlib because integration and package share name

* Fix more tests

* Update .coveragerc and CODEOWNERS

homeassistant/components/demo/switch.py

@@ -0,0 +1,73 @@
+"""
+Demo platform that has two fake switches.
+
+For more details about this platform, please refer to the documentation
+https://home-assistant.io/components/demo/
+"""
+from homeassistant.components.switch import SwitchDevice
+from homeassistant.const import DEVICE_DEFAULT_NAME
+
+
+def setup_platform(hass, config, add_entities_callback, discovery_info=None):
+    """Set up the demo switches."""
+    add_entities_callback([
+        DemoSwitch('Decorative Lights', True, None, True),
+        DemoSwitch('AC', False, 'mdi:air-conditioner', False)
+    ])
+
+
+class DemoSwitch(SwitchDevice):
+    """Representation of a demo switch."""
+
+    def __init__(self, name, state, icon, assumed):
+        """Initialize the Demo switch."""
+        self._name = name or DEVICE_DEFAULT_NAME
+        self._state = state
+        self._icon = icon
+        self._assumed = assumed
+
+    @property
+    def should_poll(self):
+        """No polling needed for a demo switch."""
+        return False
+
+    @property
+    def name(self):
+        """Return the name of the device if any."""
+        return self._name
+
+    @property
+    def icon(self):
+        """Return the icon to use for device if any."""
+        return self._icon
+
+    @property
+    def assumed_state(self):
+        """Return if the state is based on assumptions."""
+        return self._assumed
+
+    @property
+    def current_power_w(self):
+        """Return the current power usage in W."""
+        if self._state:
+            return 100
+
+    @property
+    def today_energy_kwh(self):
+        """Return the today total energy usage in kWh."""
+        return 15
+
+    @property
+    def is_on(self):
+        """Return true if switch is on."""
+        return self._state
+
+    def turn_on(self, **kwargs):
+        """Turn the switch on."""
+        self._state = True
+        self.schedule_update_ha_state()
+
+    def turn_off(self, **kwargs):
+        """Turn the device off."""
+        self._state = False
+        self.schedule_update_ha_state()