Adds filesize component (#12211)

* Create filesize.py

* Update filesize.py

* Updates filesize

Addresses issues raised in review

* Update .coveragerc

* Addresses requested changes

Addresses the changes requested by @Baloob.
Additionally the file size in bytes is now available in attributes.

* Create test_filesize.py

This isn't working yet

* Update test_filesize.py

* Update test_filesize.py

* Update test_filesize.py

* Update test_filesize.py

* Update test_filesize.py

* Update test_filesize.py

* fixed valid file test

* Update test_filesize.py

* Fix indentation

Fix incorrect indentation in setup

* Update filesize.py

* Update filesize.py

.coveragerc

@@ -558,6 +558,7 @@ omit =
     homeassistant/components/sensor/etherscan.py
     homeassistant/components/sensor/fastdotcom.py
     homeassistant/components/sensor/fedex.py
+    homeassistant/components/sensor/filesize.py
     homeassistant/components/sensor/fitbit.py
     homeassistant/components/sensor/fixer.py
     homeassistant/components/sensor/fritzbox_callmonitor.py

homeassistant/components/sensor/filesize.py

@@ -0,0 +1,92 @@
+"""
+Sensor for monitoring the size of a file.
+
+For more details about this platform, please refer to the documentation at
+https://home-assistant.io/components/sensor.filesize/
+"""
+import datetime
+import logging
+import os
+
+import voluptuous as vol
+
+from homeassistant.helpers.entity import Entity
+import homeassistant.helpers.config_validation as cv
+from homeassistant.components.sensor import PLATFORM_SCHEMA
+
+_LOGGER = logging.getLogger(__name__)
+
+
+CONF_FILE_PATHS = 'file_paths'
+ICON = 'mdi:file'
+
+PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
+    vol.Required(CONF_FILE_PATHS):
+        vol.All(cv.ensure_list, [cv.isfile]),
+})
+
+
+def setup_platform(hass, config, add_devices, discovery_info=None):
+    """Set up the file size sensor."""
+    sensors = []
+    for path in config.get(CONF_FILE_PATHS):
+        if not hass.config.is_allowed_path(path):
+            _LOGGER.error(
+                "Filepath %s is not valid or allowed", path)
+            continue
+        else:
+            sensors.append(Filesize(path))
+
+    if sensors:
+        add_devices(sensors, True)
+
+
+class Filesize(Entity):
+    """Encapsulates file size information."""
+
+    def __init__(self, path):
+        """Initialize the data object."""
+        self._path = path   # Need to check its a valid path
+        self._size = None
+        self._last_updated = None
+        self._name = path.split("/")[-1]
+        self._unit_of_measurement = 'MB'
+
+    def update(self):
+        """Update the sensor."""
+        statinfo = os.stat(self._path)
+        self._size = statinfo.st_size
+        last_updated = datetime.datetime.fromtimestamp(statinfo.st_mtime)
+        self._last_updated = last_updated.isoformat()
+
+    @property
+    def name(self):
+        """Return the name of the sensor."""
+        return self._name
+
+    @property
+    def state(self):
+        """Return the size of the file in MB."""
+        decimals = 2
+        state_mb = round(self._size/1e6, decimals)
+        return state_mb
+
+    @property
+    def icon(self):
+        """Icon to use in the frontend, if any."""
+        return ICON
+
+    @property
+    def device_state_attributes(self):
+        """Return other details about the sensor state."""
+        attr = {
+            'path': self._path,
+            'last_updated': self._last_updated,
+            'bytes': self._size,
+            }
+        return attr
+
+    @property
+    def unit_of_measurement(self):
+        """Return the unit of measurement of this entity, if any."""
+        return self._unit_of_measurement

tests/components/sensor/test_filesize.py

@@ -0,0 +1,58 @@
+"""The tests for the filesize sensor."""
+import unittest
+import os
+
+from homeassistant.components.sensor.filesize import CONF_FILE_PATHS
+from homeassistant.setup import setup_component
+from tests.common import get_test_home_assistant
+
+
+TEST_DIR = os.path.join(os.path.dirname(__file__))
+TEST_FILE = os.path.join(TEST_DIR, 'mock_file_test_filesize.txt')
+
+
+def create_file(path):
+    """Create a test file."""
+    with open(path, 'w') as test_file:
+        test_file.write("test")
+
+
+class TestFileSensor(unittest.TestCase):
+    """Test the filesize sensor."""
+
+    def setup_method(self, method):
+        """Set up things to be run when tests are started."""
+        self.hass = get_test_home_assistant()
+        self.hass.config.whitelist_external_dirs = set((TEST_DIR))
+
+    def teardown_method(self, method):
+        """Stop everything that was started."""
+        if os.path.isfile(TEST_FILE):
+            os.remove(TEST_FILE)
+        self.hass.stop()
+
+    def test_invalid_path(self):
+        """Test that an invalid path is caught."""
+        config = {
+            'sensor': {
+                'platform': 'filesize',
+                CONF_FILE_PATHS: ['invalid_path']}
+        }
+        self.assertTrue(
+            setup_component(self.hass, 'sensor', config))
+        assert len(self.hass.states.entity_ids()) == 0
+
+    def test_valid_path(self):
+        """Test for a valid path."""
+        create_file(TEST_FILE)
+        config = {
+            'sensor': {
+                'platform': 'filesize',
+                CONF_FILE_PATHS: [TEST_FILE]}
+        }
+        self.assertTrue(
+            setup_component(self.hass, 'sensor', config))
+        assert len(self.hass.states.entity_ids()) == 1
+        state = self.hass.states.get('sensor.mock_file_test_filesizetxt')
+        assert state.state == '0.0'
+        assert state.attributes.get('bytes') == 4