Add sensor to show how many clients are connected. (#4430)

* Add sensor to show how many clients are connected.

* Lint

* Fix tests

homeassistant/components/sensor/api_streams.py

@@ -0,0 +1,61 @@
+"""Entity to track connections to stream API."""
+import asyncio
+import logging
+
+from homeassistant.helpers.entity import Entity
+
+
+class StreamHandler(logging.Handler):
+    """Check log messages for stream connect/disconnect."""
+
+    def __init__(self, entity):
+        """Initialize handler."""
+        super().__init__()
+        self.entity = entity
+        self.count = 0
+
+    def handle(self, record):
+        """Handle a log message."""
+        if not record.msg.startswith('STREAM'):
+            return
+
+        if record.msg.endswith('ATTACHED'):
+            self.entity.count += 1
+        elif record.msg.endswith('RESPONSE CLOSED'):
+            self.entity.count -= 1
+
+        self.entity.schedule_update_ha_state()
+
+
+@asyncio.coroutine
+def async_setup_platform(hass, config, async_add_devices, discovery_info=None):
+    """Set up the logger for filters."""
+    entity = APICount()
+
+    logging.getLogger('homeassistant.components.api').addHandler(
+        StreamHandler(entity))
+
+    yield from async_add_devices([entity])
+
+
+class APICount(Entity):
+    """Entity to represent how many people are connected to stream API."""
+
+    def __init__(self):
+        """Initialize the API count."""
+        self.count = 0
+
+    @property
+    def name(self):
+        """Return name of entity."""
+        return "Connected clients"
+
+    @property
+    def state(self):
+        """Return current API count."""
+        return self.count
+
+    @property
+    def unit_of_measurement(self):
+        """Unit of measurement."""
+        return "clients"

tests/components/sensor/test_api_streams.py

@@ -0,0 +1,39 @@
+import asyncio
+import logging
+
+from homeassistant.bootstrap import async_setup_component
+from tests.common import assert_setup_component
+
+
+@asyncio.coroutine
+def test_api_streams(hass):
+    """Test API streams."""
+    log = logging.getLogger('homeassistant.components.api')
+
+    with assert_setup_component(1):
+        yield from async_setup_component(hass, 'sensor', {
+            'sensor': {
+                'platform': 'api_streams',
+            }
+        })
+
+    state = hass.states.get('sensor.connected_clients')
+    assert state.state == '0'
+
+    log.debug('STREAM 1 ATTACHED')
+    yield from hass.async_block_till_done()
+
+    state = hass.states.get('sensor.connected_clients')
+    assert state.state == '1'
+
+    log.debug('STREAM 1 ATTACHED')
+    yield from hass.async_block_till_done()
+
+    state = hass.states.get('sensor.connected_clients')
+    assert state.state == '2'
+
+    log.debug('STREAM 1 RESPONSE CLOSED')
+    yield from hass.async_block_till_done()
+
+    state = hass.states.get('sensor.connected_clients')
+    assert state.state == '1'