Adds London_air component (#9020)

* Adds London_air component

* Fix lints

* Reduce fixture

* Fix config validate

* Fix naming

* fix tests

tests/components/sensor/test_london_air.py

@@ -0,0 +1,41 @@
+"""The tests for the tube_state platform."""
+import unittest
+import requests_mock
+
+from homeassistant.components.sensor.london_air import (
+    CONF_LOCATIONS, URL)
+from homeassistant.setup import setup_component
+from tests.common import load_fixture, get_test_home_assistant
+
+VALID_CONFIG = {
+    'platform': 'london_air',
+    CONF_LOCATIONS: [
+        'Merton',
+    ]
+}
+
+
+class TestLondonAirSensor(unittest.TestCase):
+    """Test the tube_state platform."""
+
+    def setUp(self):
+        """Initialize values for this testcase class."""
+        self.hass = get_test_home_assistant()
+        self.config = VALID_CONFIG
+
+    def tearDown(self):
+        """Stop everything that was started."""
+        self.hass.stop()
+
+    @requests_mock.Mocker()
+    def test_setup(self, mock_req):
+        """Test for operational tube_state sensor with proper attributes."""
+        mock_req.get(URL, text=load_fixture('london_air.json'))
+        self.assertTrue(
+            setup_component(self.hass, 'sensor', {'sensor': self.config}))
+
+        state = self.hass.states.get('sensor.merton')
+        assert state.state == 'Low'
+        assert state.attributes.get('updated') == '2017-08-03 03:00:00'
+        assert state.attributes.get('sites') == 2
+        assert state.attributes.get('data')[0]['site_code'] == 'ME2'