curds: Implement an artist playlist node

Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>

curds/playlist/artist.py

@@ -0,0 +1,20 @@
+# Copyright 2019 (c) Anna Schumaker.
+from . import node
+from . import playlist
+from .. import notify
+
+class ArtistNode(node.PlaylistNode):
+    def __init__(self):
+        node.PlaylistNode.__init__(self, "Artists", "system-users")
+        notify.register("new-track", self.new_track)
+
+    def new_track(self, track):
+        plist = self.lookup(track["albumartist"])
+        if plist == None:
+            plist = playlist.Playlist(track["albumartist"], self.icon)
+            self.insert_child(plist)
+        plist.add(track)
+
+    def reset(self):
+        node.PlaylistNode.reset(self)
+        notify.register("new-track", self.new_track)

curds/playlist/test_artist.py

@@ -0,0 +1,48 @@
+# Copyright 2019 (c) Anna Schumaker
+from . import artist
+from . import node
+from .. import notify
+from .. import tags
+import os
+import unittest
+
+test_library = os.path.abspath("./trier/Test Library")
+test_album   = os.path.join("Test Album 1", "01 - Test Track 01.ogg")
+test_album2  = os.path.join("Test Album 2", "01 - Test Track 01.ogg")
+
+class TestArtistPlaylist(unittest.TestCase):
+    def test_artist_node(self):
+        notify.registered.clear()
+        tags.clear()
+
+        anode = artist.ArtistNode()
+        self.assertIsInstance(anode, node.PlaylistNode)
+        self.assertEqual(anode.name, "Artists")
+        self.assertEqual(anode.icon, "system-users")
+
+        track1 = tags.Track.lookup(os.path.join(test_library, "Test Artist 01", test_album))
+        self.assertEqual(anode.n_children(), 1)
+
+        plist = anode.nth_child(0)
+        self.assertEqual(plist.name, "Test Artist 01")
+        self.assertEqual(plist.icon, "system-users")
+        self.assertEqual(len(plist), 1)
+        self.assertEqual(plist[0], track1)
+
+
+        track2 = tags.Track.lookup(os.path.join(test_library, "Test Artist 02", test_album))
+        self.assertEqual(anode.n_children(), 2)
+
+        plist = anode.nth_child(1)
+        self.assertEqual(plist.name, "Test Artist 02")
+        self.assertEqual(len(plist), 1)
+
+
+        track3 = tags.Track.lookup(os.path.join(test_library, "Test Artist 02", test_album2))
+        self.assertEqual(anode.n_children(), 2)
+        self.assertEqual(len(plist), 2)
+
+        notify.cancel("new-track", anode.new_track)
+        anode.reset()
+        self.assertEqual(anode.n_children(), 0)
+        self.assertIn((anode.new_track, False), notify.registered["new-track"])