Add warning for slow platforms/components (#6467)

* Add warning for slow platforms/components

* Add test for slow component setup.

* Add test for slow platform setup

* Fix tests on Py34

tests/test_setup.py

@@ -407,3 +407,23 @@ def test_component_cannot_depend_config(hass):
     result = yield from setup._async_process_dependencies(
         hass, None, 'test', ['config'])
     assert not result
+
+
+@asyncio.coroutine
+def test_component_warn_slow_setup(hass):
+    """Warn we log when a component setup takes a long time."""
+    loader.set_component('test_component1', MockModule('test_component1'))
+    with mock.patch.object(hass.loop, 'call_later', mock.MagicMock()) \
+            as mock_call:
+        result = yield from setup.async_setup_component(
+            hass, 'test_component1', {})
+        assert result
+        assert mock_call.called
+        assert len(mock_call.mock_calls) == 2
+
+        timeout, logger_method = mock_call.mock_calls[0][1][:2]
+
+        assert timeout == setup.SLOW_SETUP_WARNING
+        assert logger_method == setup._LOGGER.warning
+
+        assert mock_call().cancel.called