db: Give QueuedTracks a custom next_track() function

So we can remove tracks from the queue as they are played.

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

db/test_user.py

@@ -248,8 +248,8 @@ class TestQueuedTracks(unittest.TestCase):
 
     def test_init(self):
         queued = db.user.Table.find("Queued Tracks")
-        self.assertIsInstance(queued, db.playlist.MappedPlaylist)
         self.assertIsInstance(queued, db.user.UserPlaylist)
+        self.assertIsInstance(queued, db.user.QueuedTracks)
         self.assertEqual(queued.name, "Queued Tracks")
         self.assertEqual(queued.icon_name, "edit-redo")
         self.assertEqual(queued.map_table, "playlist_map")
@@ -278,6 +278,20 @@ class TestQueuedTracks(unittest.TestCase):
         self.assertEqual(queued.get_tracks(), [ ])
         self.assertEqual(self.removed, (track, False))
 
+    def test_next_track(self):
+        queued = db.user.Table.find("Queued Tracks")
+        queued.add_track(db.make_fake_track(1, 1, "Test 1", "/a/b/c/1.ogg"))
+        queued.add_track(db.make_fake_track(2, 2, "Test 2", "/a/b/c/2.ogg"))
+        queued.add_track(db.make_fake_track(3, 3, "Test 3", "/a/b/c/3.ogg"))
+
+        self.assertEqual(queued.next_track(), db.track.Table.lookup("/a/b/c/1.ogg"))
+        self.assertEqual(queued.get_n_tracks(), 2)
+        self.assertEqual(queued.next_track(), db.track.Table.lookup("/a/b/c/2.ogg"))
+        self.assertEqual(queued.get_n_tracks(), 1)
+        self.assertEqual(queued.next_track(), db.track.Table.lookup("/a/b/c/3.ogg"))
+        self.assertEqual(queued.get_n_tracks(), 0)
+        self.assertIsNone(queued.next_track())
+
 
 class TestUserPlaylist(unittest.TestCase):
     def track_added(self, plist, added):

db/user.py

@@ -99,6 +99,16 @@ class Previous(UserPlaylist):
         return super().next_track()
 
 
+class QueuedTracks(UserPlaylist):
+    def __init__(self, row):
+        UserPlaylist.__init__(self, row, "edit-redo", "playlist_map")
+
+    def next_track(self):
+        if track := super().next_track():
+            self.remove_track(track)
+        return track
+
+
 class UserTable(playlist.Model):
     def __init__(self):
         playlist.Model.__init__(self, "playlists", "sort")
@@ -145,7 +155,7 @@ class UserTable(playlist.Model):
         elif row["name"] == "Previous":
             return Previous(row)
         elif row["name"] == "Queued Tracks":
-            return UserPlaylist(row, "edit-redo", "playlist_map")
+            return QueuedTracks(row)
         return UserPlaylist(row, "audio-x-generic", "playlist_map")
 
     def do_insert(self, plstate, name):