core: Add tests for change_track failing in about-to-finish

mopidy/core/playback.py

@@ -254,13 +254,19 @@ class PlaybackController(object):
         pending = self.core.tracklist.eot_track(self._current_tl_track)
         while pending:
             # TODO: Avoid infinite loops if all tracks are unplayable.
-            # TODO: Wrap backend call in error handling.
             backend = self._get_backend(pending)
-            if backend and backend.playback.change_track(pending.track).get():
-                self._pending_tl_track = pending
-                break
-            else:
-                self.core.tracklist._mark_unplayable(pending)
+            if not backend:
+                continue
+
+            try:
+                if backend.playback.change_track(pending.track).get():
+                    self._pending_tl_track = pending
+                    break
+            except Exception:
+                logger.exception('%s backend caused an exception.',
+                                 backend.actor_ref.actor_class.__name__)
+
+            self.core.tracklist._mark_unplayable(pending)
             pending = self.core.tracklist.eot_track(pending)
 
     def _on_tracklist_change(self):

tests/core/test_playback.py

@@ -333,6 +333,34 @@ class TestOnAboutToFinish(BaseTest):
 
         self.assertIn(tl_track, self.core.tracklist.tl_tracks)
 
+    def test_on_about_to_finish_skips_over_change_track_error(self):
+        # Trigger an exception in translate_uri.
+        track = Track(uri='dummy:error', length=1234)
+        self.core.tracklist.add(tracks=[track], at_position=1)
+
+        tl_tracks = self.core.tracklist.get_tl_tracks()
+
+        self.core.playback.play(tl_tracks[0])
+        self.replay_events()
+
+        self.trigger_about_to_finish()
+
+        assert self.core.playback.get_current_tl_track() == tl_tracks[2]
+
+    def test_on_about_to_finish_skips_over_change_track_unplayable(self):
+        # Makes translate_uri return None.
+        track = Track(uri='dummy:unplayable', length=1234)
+        self.core.tracklist.add(tracks=[track], at_position=1)
+
+        tl_tracks = self.core.tracklist.get_tl_tracks()
+
+        self.core.playback.play(tl_tracks[0])
+        self.replay_events()
+
+        self.trigger_about_to_finish()
+
+        assert self.core.playback.get_current_tl_track() == tl_tracks[2]
+
 
 class TestConsumeHandling(BaseTest):