add test for mqtt+json switch

tests/components/sensor/test_mqtt.py

@@ -56,5 +56,4 @@ class TestSensorMQTT(unittest.TestCase):
         state = self.hass.states.get('sensor.test')
 
         self.assertEqual('100', state.state)
-        self.assertEqual('fav unit',
+
-                         state.attributes.get('unit_of_measurement'))

tests/components/switch/test_mqtt.py

@@ -80,3 +80,31 @@ class TestSensorMQTT(unittest.TestCase):
                          self.mock_publish.mock_calls[-1][1])
         state = self.hass.states.get('switch.test')
         self.assertEqual(STATE_OFF, state.state)
+
+    def test_controlling_state_via_topic_and_json_message(self):
+        self.assertTrue(switch.setup(self.hass, {
+            'switch': {
+                'platform': 'mqtt',
+                'name': 'test',
+                'state_topic': 'state-topic',
+                'command_topic': 'command-topic',
+                'payload_on': 'beer on',
+                'payload_off': 'beer off',
+                'state_format': 'json:val'
+            }
+        }))
+
+        state = self.hass.states.get('switch.test')
+        self.assertEqual(STATE_OFF, state.state)
+
+        fire_mqtt_message(self.hass, 'state-topic', '{"val":"beer on"}')
+        self.hass.pool.block_till_done()
+
+        state = self.hass.states.get('switch.test')
+        self.assertEqual(STATE_ON, state.state)
+
+        fire_mqtt_message(self.hass, 'state-topic', '{"val":"beer off"}')
+        self.hass.pool.block_till_done()
+
+        state = self.hass.states.get('switch.test')
+        self.assertEqual(STATE_OFF, state.state)