Migrate core from threads to async awesomeness (#3248)

* Add event loop to the core

* Add block_till_done to HA core object

* Fix some tests

* Linting core

* Fix statemachine tests

* Core test fixes

* fix block_till_done to wait for loop and queue to empty

* fix test_core for passing, and correct start/stop/block_till_done

* Fix remote tests

* Fix tests: block_till_done

* Fix linting

* Fix more tests

* Fix final linting

* Fix remote test

* remove unnecessary import

* reduce sleep to avoid slowing down the tests excessively

* fix remaining tests to wait for non-threadsafe operations

* Add async_ doc strings for event loop / coroutine info

* Fix command line test to block for the right timeout

* Fix py3.4.2 loop var access

* Fix SERVICE_CALL_LIMIT being in effect for other tests

* Fix lint errors

* Fix lint error with proper placement

* Fix slave start to not start a timer

* Add asyncio compatible listeners.

* Increase min Python version to 3.4.2

* Move async backports to util

* Add backported async tests

* Fix linting

* Simplify Python version check

* Fix lint

* Remove unneeded try/except and queue listener appproriately.

* Fix tuple vs. list unorderable error on version compare.

* Fix version tests

tests/common.py

@@ -1,10 +1,12 @@
 """Test the helper method for writing tests."""
+import asyncio
 import os
 from datetime import timedelta
 from unittest import mock
 from unittest.mock import patch
 from io import StringIO
 import logging
+import threading
 
 from homeassistant import core as ha, loader
 from homeassistant.bootstrap import setup_component
@@ -29,11 +31,13 @@ def get_test_config_dir(*add_path):
 
 def get_test_home_assistant(num_threads=None):
     """Return a Home Assistant object pointing at test config dir."""
+    loop = asyncio.new_event_loop()
+
     if num_threads:
         orig_num_threads = ha.MIN_WORKER_THREAD
         ha.MIN_WORKER_THREAD = num_threads
 
-    hass = ha.HomeAssistant()
+    hass = ha.HomeAssistant(loop)
 
     if num_threads:
         ha.MIN_WORKER_THREAD = orig_num_threads
@@ -49,6 +53,26 @@ def get_test_home_assistant(num_threads=None):
     if 'custom_components.test' not in loader.AVAILABLE_COMPONENTS:
         loader.prepare(hass)
 
+    # FIXME should not be a daemon. Means hass.stop() not called in teardown
+    threading.Thread(name="LoopThread", target=loop.run_forever,
+                     daemon=True).start()
+
+    orig_start = hass.start
+
+    @asyncio.coroutine
+    def fake_stop():
+        yield None
+
+    def start_hass():
+        """Helper to start hass."""
+        with patch.object(hass.loop, 'run_forever', return_value=None):
+            with patch.object(hass, 'async_stop', return_value=fake_stop()):
+                with patch.object(ha, 'create_timer', return_value=None):
+                    orig_start()
+                    hass.block_till_done()
+
+    hass.start = start_hass
+
     return hass