trackdb: Give TrackAllocators a function to list tracks in a library

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

trackdb/allocator.py

@@ -40,6 +40,12 @@ class TrackAllocator:
         except Exception as e:
             pass
 
+    def list_tracks(self, lib):
+        with self.lock:
+            for (id, track) in self.tracks.items():
+                if track.library ==lib:
+                    yield track
+
     def remove(self, track):
         with self.lock:
             del self.tracks[track.trackid]

trackdb/test_allocator.py

@@ -46,6 +46,9 @@ class TestTrackAllocator(unittest.TestCase):
 
         self.assertIsNone(alloc.allocate(lib, test_tracks / "No Such File"))
         self.assertEqual(self.added, track2)
+        self.assertEqual([ t for t in alloc.list_tracks(lib) ], [ track, track2 ])
+        track.library = None
+        self.assertEqual([ t for t in alloc.list_tracks(lib) ], [ track2 ])
 
         alloc.remove(track)
         self.assertEqual(alloc[0], None)