core: Add playlists.as_list() and playlists.get_items(uri)

docs/changelog.rst

@@ -77,6 +77,17 @@ v1.0.0 (UNRELEASED)
   :meth:`mopidy.core.LibraryController.find_exact` to normalize and warn about
   bad queries from clients. (Fixes: :issue:`1067`, PR: :issue:`1073`)
 
+- Add :meth:`mopidy.core.PlaylistsController.as_list`. (Fixes: :issue:`1057`,
+  PR: :issue:`1075`)
+
+- Add :meth:`mopidy.core.PlaylistsController.get_items`. (Fixes: :issue:`1057`,
+  PR: :issue:`1075`)
+
+- **Deprecated:** :meth:`mopidy.core.PlaylistsController.get_playlists`. Use
+  :meth:`~mopidy.core.PlaylistsController.as_list` and
+  :meth:`~mopidy.core.PlaylistsController.get_items` instead. (Fixes:
+  :issue:`1057`, PR: :issue:`1075`)
+
 **Backend API**
 
 - Remove default implementation of

mopidy/core/playlists.py

@@ -16,12 +16,52 @@ class PlaylistsController(object):
         self.backends = backends
         self.core = core
 
-    """
-    Get the available playlists.
+    def as_list(self):
+        """
+        Get a list of the currently available playlists.
+
+        Returns a list of :class:`~mopidy.models.Ref` objects referring to the
+        playlists. In other words, no information about the playlists' content
+        is given.
+
+        :rtype: list of :class:`mopidy.models.Ref`
+
+        .. versionadded:: 1.0
+        """
+        futures = [
+            b.playlists.as_list()
+            for b in self.backends.with_playlists.values()]
+        results = pykka.get_all(futures)
+        return list(itertools.chain(*results))
+
+    def get_items(self, uri):
+        """
+        Get the items in a playlist specified by ``uri``.
+
+        Returns a list of :class:`~mopidy.models.Ref` objects referring to the
+        playlist's items.
+
+        If a playlist with the given ``uri`` doesn't exist, it returns
+        :class:`None`.
+
+        :rtype: list of :class:`mopidy.models.Ref`, or :class:`None`
+
+        .. versionadded:: 1.0
+        """
+        uri_scheme = urlparse.urlparse(uri).scheme
+        backend = self.backends.with_playlists.get(uri_scheme, None)
+        if backend:
+            return backend.playlists.get_items(uri).get()
 
-    Returns a list of :class:`mopidy.models.Playlist`.
-    """
     def get_playlists(self, include_tracks=True):
+        """
+        Get the available playlists.
+
+        :rtype: list of :class:`mopidy.models.Playlist`
+
+        .. deprecated:: 1.0
+            Use :meth:`as_list` and :meth:`get_items` instead.
+        """
         futures = [b.playlists.playlists
                    for b in self.backends.with_playlists.values()]
         results = pykka.get_all(futures)
@@ -33,7 +73,7 @@ class PlaylistsController(object):
     playlists = deprecated_property(get_playlists)
     """
     .. deprecated:: 1.0
-        Use :meth:`get_playlists` instead.
+        Use :meth:`as_list` and :meth:`get_items` instead.
     """
 
     def create(self, name, uri_scheme=None):

tests/core/test_playlists.py

@@ -5,19 +5,37 @@ import unittest
 import mock
 
 from mopidy import backend, core
-from mopidy.models import Playlist, Track
+from mopidy.models import Playlist, Ref, Track
 
 
 class PlaylistsTest(unittest.TestCase):
     def setUp(self):  # noqa: N802
+        self.plr1a = Ref.playlist(name='A', uri='dummy1:pl:a')
+        self.plr1b = Ref.playlist(name='B', uri='dummy1:pl:b')
+        self.plr2a = Ref.playlist(name='A', uri='dummy2:pl:a')
+        self.plr2b = Ref.playlist(name='B', uri='dummy2:pl:b')
+
+        self.pl1a = Playlist(name='A', tracks=[Track(uri='dummy1:t:a')])
+        self.pl1b = Playlist(name='B', tracks=[Track(uri='dummy1:t:b')])
+        self.pl2a = Playlist(name='A', tracks=[Track(uri='dummy2:t:a')])
+        self.pl2b = Playlist(name='B', tracks=[Track(uri='dummy2:t:b')])
+
+        self.sp1 = mock.Mock(spec=backend.PlaylistsProvider)
+        self.sp1.as_list.return_value.get.return_value = [
+            self.plr1a, self.plr1b]
+        self.sp1.playlists.get.return_value = [self.pl1a, self.pl1b]
+
+        self.sp2 = mock.Mock(spec=backend.PlaylistsProvider)
+        self.sp2.as_list.return_value.get.return_value = [
+            self.plr2a, self.plr2b]
+        self.sp2.playlists.get.return_value = [self.pl2a, self.pl2b]
+
         self.backend1 = mock.Mock()
         self.backend1.uri_schemes.get.return_value = ['dummy1']
-        self.sp1 = mock.Mock(spec=backend.PlaylistsProvider)
         self.backend1.playlists = self.sp1
 
         self.backend2 = mock.Mock()
         self.backend2.uri_schemes.get.return_value = ['dummy2']
-        self.sp2 = mock.Mock(spec=backend.PlaylistsProvider)
         self.backend2.playlists = self.sp2
 
         # A backend without the optional playlists provider
@@ -26,17 +44,34 @@ class PlaylistsTest(unittest.TestCase):
         self.backend3.has_playlists().get.return_value = False
         self.backend3.playlists = None
 
-        self.pl1a = Playlist(name='A', tracks=[Track(uri='dummy1:a')])
-        self.pl1b = Playlist(name='B', tracks=[Track(uri='dummy1:b')])
-        self.sp1.playlists.get.return_value = [self.pl1a, self.pl1b]
-
-        self.pl2a = Playlist(name='A', tracks=[Track(uri='dummy2:a')])
-        self.pl2b = Playlist(name='B', tracks=[Track(uri='dummy2:b')])
-        self.sp2.playlists.get.return_value = [self.pl2a, self.pl2b]
-
         self.core = core.Core(mixer=None, backends=[
             self.backend3, self.backend1, self.backend2])
 
+    def test_as_list_combines_result_from_backends(self):
+        result = self.core.playlists.as_list()
+
+        self.assertIn(self.plr1a, result)
+        self.assertIn(self.plr1b, result)
+        self.assertIn(self.plr2a, result)
+        self.assertIn(self.plr2b, result)
+
+    def test_get_items_selects_the_matching_backend(self):
+        ref = Ref.track()
+        self.sp2.get_items.return_value.get.return_value = [ref]
+
+        result = self.core.playlists.get_items('dummy2:pl:a')
+
+        self.assertEqual([ref], result)
+        self.assertFalse(self.sp1.get_items.called)
+        self.sp2.get_items.assert_called_once_with('dummy2:pl:a')
+
+    def test_get_items_with_unknown_uri_scheme_does_nothing(self):
+        result = self.core.playlists.get_items('unknown:a')
+
+        self.assertIsNone(result)
+        self.assertFalse(self.sp1.delete.called)
+        self.assertFalse(self.sp2.delete.called)
+
     def test_get_playlists_combines_result_from_backends(self):
         result = self.core.playlists.playlists