curds: Only trigger "on-scan" when new tracks are created

This cuts down on unnecessary notifications for tracks that already
exist.

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

curds/playlist/library.py

@@ -16,8 +16,9 @@ class LibraryPlaylist(playlist.Playlist):
 
     def thread_add(self, path):
         track = tags.Track.add(path)
-        self.add(track)
-        self.notify("on-scan", track)
+        if track != None:
+            self.add(track)
+            self.notify("on-scan", track)
 
     def thread_scan(self):
         for dirname, subdirs, files in os.walk(self.name):

curds/playlist/test_library.py

@@ -38,3 +38,8 @@ class TestLibraryPlaylist(unittest.TestCase):
         self.assertEqual(len(plist), 1250)
         self.assertEqual(self.scan_count, 1250)
         self.assertEqual(plist.runtime(), "1 hour, 54 minutes, 35 seconds")
+
+        plist.scan()
+        library.library_thread.join()
+        self.assertEqual(len(plist), 1250)
+        self.assertEqual(self.scan_count, 1250)