Add simple statsd tests

These are not very amazing, but at least exercise the code a little
to make sure I didn't break anything. Hopefully they're useful in the
future too.

tests/components/test_statsd.py

@@ -0,0 +1,83 @@
+"""
+tests.components.test_statsd
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Tests statsd feeder.
+"""
+import unittest
+from unittest import mock
+
+import homeassistant.components.statsd as statsd
+from homeassistant.const import STATE_ON, STATE_OFF, EVENT_STATE_CHANGED
+
+
+class TestStatsd(unittest.TestCase):
+    @mock.patch('statsd.Connection')
+    @mock.patch('statsd.Gauge')
+    def test_statsd_setup_full(self, mock_gauge, mock_connection):
+        config = {
+            'statsd': {
+                'host': 'host',
+                'port': 123,
+                'sample_rate': 1,
+                'prefix': 'foo',
+            }
+        }
+        hass = mock.MagicMock()
+        self.assertTrue(statsd.setup(hass, config))
+        mock_connection.assert_called_once_with(host='host', port=123,
+                                                sample_rate=1,
+                                                disabled=False)
+        mock_gauge.assert_called_once_with('foo',
+                                           mock_connection.return_value)
+        self.assertTrue(hass.bus.listen.called)
+        self.assertEqual(EVENT_STATE_CHANGED,
+                         hass.bus.listen.call_args_list[0][0][0])
+
+    @mock.patch('statsd.Connection')
+    @mock.patch('statsd.Gauge')
+    def test_statsd_setup_defaults(self, mock_gauge, mock_connection):
+        config = {
+            'statsd': {
+                'host': 'host',
+            }
+        }
+        hass = mock.MagicMock()
+        self.assertTrue(statsd.setup(hass, config))
+        mock_connection.assert_called_once_with(
+            host='host',
+            port=statsd.DEFAULT_PORT,
+            sample_rate=statsd.DEFAULT_RATE,
+            disabled=False)
+        mock_gauge.assert_called_once_with(statsd.DEFAULT_PREFIX,
+                                           mock_connection.return_value)
+        self.assertTrue(hass.bus.listen.called)
+
+    @mock.patch('statsd.Connection')
+    @mock.patch('statsd.Gauge')
+    def test_event_listener(self, mock_gauge, mock_connection):
+        config = {
+            'statsd': {
+                'host': 'host',
+            }
+        }
+        hass = mock.MagicMock()
+        statsd.setup(hass, config)
+        self.assertTrue(hass.bus.listen.called)
+        handler_method = hass.bus.listen.call_args_list[0][0][1]
+
+        valid = {'1': 1,
+                 '1.0': 1.0,
+                 STATE_ON: 1,
+                 STATE_OFF: 0}
+        for in_, out in valid.items():
+            state = mock.MagicMock(state=in_)
+            handler_method(mock.MagicMock(data={'new_state': state}))
+            mock_gauge.return_value.send.assert_called_once_with(
+                state.entity_id, out)
+            mock_gauge.return_value.send.reset_mock()
+
+        for invalid in ('foo', '', object):
+            state = mock.MagicMock(state=invalid)
+            handler_method(mock.MagicMock(data={'new_state': state}))
+            self.assertFalse(mock_gauge.return_value.send.called)