Fix OwnTracks race condition (#24303)

* Fix OwnTracks race condition

* Lint

homeassistant/components/owntracks/__init__.py

@@ -192,6 +192,7 @@ class OwnTracksContext:
         self.region_mapping = region_mapping
         self.events_only = events_only
         self.mqtt_topic = mqtt_topic
+        self._pending_msg = []
 
     @callback
     def async_valid_accuracy(self, message):
@@ -222,10 +223,19 @@ class OwnTracksContext:
 
         return True
 
+    @callback
+    def set_async_see(self, func):
+        """Set a new async_see function."""
+        self.async_see = func
+        for msg in self._pending_msg:
+            func(**msg)
+        self._pending_msg.clear()
+
+    # pylint: disable=method-hidden
     @callback
     def async_see(self, **data):
         """Send a see message to the device tracker."""
-        raise NotImplementedError
+        self._pending_msg.append(data)
 
     @callback
     def async_see_beacons(self, hass, dev_id, kwargs_param):

homeassistant/components/owntracks/device_tracker.py

@@ -36,7 +36,7 @@ async def async_setup_entry(hass, entry, async_add_entities):
         )
         async_add_entities([entity])
 
-    hass.data[OT_DOMAIN]['context'].async_see = _receive_data
+    hass.data[OT_DOMAIN]['context'].set_async_see(_receive_data)
 
     # Restore previously loaded devices
     dev_reg = await device_registry.async_get_registry(hass)

tests/components/owntracks/test_init.py

@@ -4,7 +4,7 @@ import asyncio
 import pytest
 
 from homeassistant.setup import async_setup_component
-
+from homeassistant.components import owntracks
 from tests.common import mock_component, MockConfigEntry
 
 MINIMAL_LOCATION_MESSAGE = {
@@ -160,3 +160,24 @@ def test_returns_error_missing_device(mock_client):
 
     json = yield from resp.json()
     assert json == []
+
+
+def test_context_delivers_pending_msg():
+    """Test that context is able to hold pending messages while being init."""
+    context = owntracks.OwnTracksContext(
+        None, None, None, None, None, None, None, None
+    )
+    context.async_see(hello='world')
+    context.async_see(world='hello')
+    received = []
+
+    context.set_async_see(lambda **data: received.append(data))
+
+    assert len(received) == 2
+    assert received[0] == {'hello': 'world'}
+    assert received[1] == {'world': 'hello'}
+
+    received.clear()
+
+    context.set_async_see(lambda **data: received.append(data))
+    assert len(received) == 0