core: Forward playlists_loaded() event from backends to frontends

mopidy/core/actor.py

@@ -5,14 +5,16 @@ import itertools
 import pykka
 
 from mopidy.audio import AudioListener, PlaybackState
+from mopidy.backends.listener import BackendListener
 
 from .library import LibraryController
+from .listener import CoreListener
 from .playback import PlaybackController
 from .playlists import PlaylistsController
 from .tracklist import TracklistController
 
 
-class Core(pykka.ThreadingActor, AudioListener):
+class Core(pykka.ThreadingActor, AudioListener, BackendListener):
     #: The library controller. An instance of
     # :class:`mopidy.core.LibraryController`.
     library = None
@@ -67,6 +69,10 @@ class Core(pykka.ThreadingActor, AudioListener):
             self.playback.state = new_state
             self.playback._trigger_track_playback_paused()
 
+    def playlists_loaded(self):
+        # Forward event from backend to frontends
+        CoreListener.send('playlists_loaded')
+
 
 class Backends(list):
     def __init__(self, backends):

tests/core/events_test.py

@@ -20,6 +20,11 @@ class BackendEventsTest(unittest.TestCase):
     def tearDown(self):
         pykka.ActorRegistry.stop_all()
 
+    def test_backends_playlists_loaded_forwards_event_to_frontends(self, send):
+        send.reset_mock()
+        self.core.playlists_loaded().get()
+        self.assertEqual(send.call_args[0][0], 'playlists_loaded')
+
     def test_pause_sends_track_playback_paused_event(self, send):
         self.core.tracklist.add(Track(uri='dummy:a'))
         self.core.playback.play().get()