browse: Add playlist browsing

This fixes Mopidy-Spotify-Tunigo compatability.

mopidy_spotify/library.py

@@ -48,6 +48,8 @@ def __init__(self, backend):
     def browse(self, uri):
         if uri == self.root_directory.uri:
             return self._root_dir_contents
+        elif uri.startswith('spotify:user:'):
+            return self._browse_playlist(uri)
         elif uri.startswith('spotify:album:'):
             return self._browse_album(uri)
         elif uri.startswith('spotify:artist:'):
@@ -66,6 +68,11 @@ def browse(self, uri):
             logger.info('Failed to browse "%s": Unknown URI type', uri)
             return []
 
+    def _browse_playlist(self, uri):
+        playlist = self._backend._session.get_playlist(uri)
+        playlist.load()
+        return list(self._get_track_refs(playlist.tracks))
+
     def _browse_album(self, uri):
         album_browser = self._backend._session.get_album(uri).browse()
         album_browser.load()

tests/test_browse.py

@@ -24,6 +24,20 @@ def test_browse_root_directory(provider):
         uri='spotify:top:artists', name='Top artists') in results
 
 
+def test_browse_playlist(
+        session_mock, sp_playlist_mock, sp_track_mock, provider):
+    session_mock.get_playlist.return_value = sp_playlist_mock
+    sp_playlist_mock.tracks = [sp_track_mock, sp_track_mock]
+
+    results = provider.browse('spotify:user:alice:playlist:foo')
+
+    session_mock.get_playlist.assert_called_once_with(
+        'spotify:user:alice:playlist:foo')
+    assert len(results) == 2
+    assert results[0] == models.Ref.track(
+        uri='spotify:track:abc', name='ABC 123')
+
+
 def test_browse_album(
         session_mock, sp_album_mock, sp_album_browser_mock, sp_track_mock,
         provider):