[youtube:watchlater] Remove unused properties and fix tests

test/test_all_urls.py

@@ -59,7 +59,7 @@ class TestAllURLsMatching(unittest.TestCase):
         self.assertMatch('www.youtube.com/NASAgovVideo/videos', ['youtube:user'])
 
     def test_youtube_feeds(self):
-        self.assertMatch('https://www.youtube.com/feed/watch_later', ['youtube:watch_later'])
+        self.assertMatch('https://www.youtube.com/feed/watch_later', ['youtube:watchlater'])
         self.assertMatch('https://www.youtube.com/feed/subscriptions', ['youtube:subscriptions'])
         self.assertMatch('https://www.youtube.com/feed/recommended', ['youtube:recommended'])
         self.assertMatch('https://www.youtube.com/my_favorites', ['youtube:favorites'])

youtube_dl/extractor/youtube.py

@@ -1657,9 +1657,8 @@ class YoutubeWatchLaterIE(YoutubePlaylistIE):
     IE_NAME = 'youtube:watchlater'
     IE_DESC = 'Youtube watch later list, ":ytwatchlater" for short (requires authentication)'
     _VALID_URL = r'https?://www\.youtube\.com/(?:feed/watch_later|playlist\?list=WL)|:ytwatchlater'
-    _FEED_NAME = 'watch_later'
-    _PLAYLIST_TITLE = 'Youtube Watch Later'
-    _PERSONAL_FEED = True
+
+    _TESTS = []  # override PlaylistIE tests
 
     def _real_extract(self, url):
         return self._extract_playlist('WL')