audio: Add stream_changed event plus tests

mopidy/audio/actor.py

@@ -317,7 +317,12 @@ class Audio(pykka.ThreadingActor):
                 str(error).decode('utf-8'), debug.decode('utf-8') or 'None')
         elif message.type == gst.MESSAGE_ELEMENT:
             if message.structure.has_name('playbin2-stream-changed'):
-                logger.debug('Playback of new stream started')
+                self._on_stream_changed(message)
+
+    def _on_stream_changed(self, message):
+        uri = message.structure['uri']
+        logger.debug('Triggering event: stream_changed(uri=%s)', uri)
+        AudioListener.send('stream_changed', uri=uri)
 
     def _on_playbin_state_changed(self, old_state, new_state, pending_state):
         if new_state == gst.STATE_READY and pending_state == gst.STATE_NULL:
@@ -349,7 +354,7 @@ class Audio(pykka.ThreadingActor):
             'state_changed', old_state=old_state, new_state=new_state)
 
     def _on_end_of_stream(self):
-        logger.debug('Triggering reached_end_of_stream event')
+        logger.debug('Triggering event: reached_end_of_stream event')
         AudioListener.send('reached_end_of_stream')
 
     def set_uri(self, uri):
@@ -476,6 +481,22 @@ class Audio(pykka.ThreadingActor):
         """
         return self._set_state(gst.STATE_NULL)
 
+    def wait_for_state_change(self):
+        """Block until any pending state changes are complete.
+
+        Should only be used by test.
+        """
+        self._playbin.get_state()
+
+    def process_messages(self):
+        """Manually process messages from bus.
+
+        Should only be used by test.
+        """
+        bus = self._playbin.get_bus()
+        while bus.have_pending():
+            self._on_message(bus, bus.pop())
+
     def _set_state(self, state):
         """
         Internal method for setting the raw GStreamer state.

mopidy/audio/listener.py

@@ -27,6 +27,16 @@ class AudioListener(listener.Listener):
         """
         pass
 
+    def stream_changed(self, uri):
+        """
+        Called whenever the end of the audio stream changes.
+
+        *MAY* be implemented by actor.
+
+        :param string uri: URI the stream has started playing.
+        """
+        pass
+
     def state_changed(self, old_state, new_state):
         """
         Called after the playback state have changed.

tests/audio/test_actor.py

@@ -1,5 +1,6 @@
 from __future__ import unicode_literals
 
+import mock
 import unittest
 
 import pygst
@@ -114,6 +115,18 @@ class AudioTest(unittest.TestCase):
     def test_invalid_output_raises_error(self):
         pass  # TODO
 
+    @mock.patch.object(audio.AudioListener, 'send')
+    def test_stream_changed_event(self, send_mock):
+        self.audio.prepare_change()
+        self.audio.set_uri(self.song_uri)
+        self.audio.start_playback()
+
+        self.audio.wait_for_state_change()
+        self.audio.process_messages().get()
+
+        call = mock.call('stream_changed', uri=self.song_uri)
+        self.assertIn(call, send_mock.call_args_list)
+
 
 class AudioStateTest(unittest.TestCase):
     def setUp(self):

tests/audio/test_listener.py

@@ -24,3 +24,6 @@ class AudioListenerTest(unittest.TestCase):
 
     def test_listener_has_default_impl_for_state_changed(self):
         self.listener.state_changed(None, None)
+
+    def test_listener_has_default_impl_for_stream_changed(self):
+        self.listener.stream_changed(None)