MQTT discovery (#5724)

* Change implementation

* Re-write

* Remove unused consts

* Update discovery.py

* Add tests

* fix other tests

* Fix check_config script test

* Lint

* Lint

tests/components/mqtt/test_discovery.py

@@ -0,0 +1,74 @@
+"""The tests for the MQTT component."""
+import asyncio
+from unittest.mock import patch
+
+from homeassistant.components.mqtt.discovery import async_start
+
+from tests.common import async_fire_mqtt_message, mock_coro
+
+
+@asyncio.coroutine
+def test_subscribing_config_topic(hass, mqtt_mock):
+    """Test setting up discovery."""
+    hass_config = {}
+    discovery_topic = 'homeassistant'
+    async_start(hass, discovery_topic, hass_config)
+    assert mqtt_mock.subscribe.called
+    call_args = mqtt_mock.subscribe.mock_calls[0][1]
+    assert call_args[0] == discovery_topic + '/#'
+    assert call_args[1] == 0
+
+
+@asyncio.coroutine
+@patch('homeassistant.components.mqtt.discovery.async_load_platform')
+def test_invalid_topic(mock_load_platform, hass, mqtt_mock):
+    """Test sending in invalid JSON."""
+    mock_load_platform.return_value = mock_coro()
+    async_start(hass, 'homeassistant', {})
+
+    async_fire_mqtt_message(hass, 'homeassistant/binary_sensor/bla/not_config',
+                            '{}')
+    yield from hass.async_block_till_done()
+    assert not mock_load_platform.called
+
+
+@asyncio.coroutine
+@patch('homeassistant.components.mqtt.discovery.async_load_platform')
+def test_invalid_json(mock_load_platform, hass, mqtt_mock, caplog):
+    """Test sending in invalid JSON."""
+    mock_load_platform.return_value = mock_coro()
+    async_start(hass, 'homeassistant', {})
+
+    async_fire_mqtt_message(hass, 'homeassistant/binary_sensor/bla/config',
+                            'not json')
+    yield from hass.async_block_till_done()
+    assert 'Unable to parse JSON' in caplog.text
+    assert not mock_load_platform.called
+
+
+@asyncio.coroutine
+@patch('homeassistant.components.mqtt.discovery.async_load_platform')
+def test_only_valid_components(mock_load_platform, hass, mqtt_mock, caplog):
+    """Test sending in invalid JSON."""
+    mock_load_platform.return_value = mock_coro()
+    async_start(hass, 'homeassistant', {})
+
+    async_fire_mqtt_message(hass, 'homeassistant/climate/bla/config', '{}')
+    yield from hass.async_block_till_done()
+    assert 'Component climate is not supported' in caplog.text
+    assert not mock_load_platform.called
+
+
+@asyncio.coroutine
+def test_correct_config_discovery(hass, mqtt_mock, caplog):
+    """Test sending in invalid JSON."""
+    async_start(hass, 'homeassistant', {})
+
+    async_fire_mqtt_message(hass, 'homeassistant/binary_sensor/bla/config',
+                            '{ "name": "Beer" }')
+    yield from hass.async_block_till_done()
+
+    state = hass.states.get('binary_sensor.beer')
+
+    assert state is not None
+    assert state.name == 'Beer'