[test] Improve shortcut processing for test playlists

* check all playlist counts, not just max
* also consider any actual playlist in the test case

test/test_download.py

@@ -35,6 +35,8 @@ from youtube_dl.utils import (
     ExtractorError,
     error_to_compat_str,
     format_bytes,
+    T,
+    traverse_obj,
     UnavailableVideoError,
 )
 from youtube_dl.extractor import get_info_extractor
@@ -120,10 +122,14 @@ def generator(test_case, tname):
 
         params = get_params(test_case.get('params', {}))
         params['outtmpl'] = tname + '_' + params['outtmpl']
-        if is_playlist and 'playlist' not in test_case:
-            params.setdefault('extract_flat', 'in_playlist')
-            params.setdefault('playlistend', test_case.get('playlist_mincount'))
-            params.setdefault('skip_download', True)
+        if is_playlist:
+            if 'playlist' not in test_case:
+                params.setdefault('extract_flat', 'in_playlist')
+                params.setdefault('skip_download', True)
+            # only process enough items for specified tests
+            pl_counts = traverse_obj(test_case, (None, ('playlist_count', 'playlist_mincount', 'playlist_maxcount', ('playlist', T(len)))))
+            if pl_counts is not None:
+                params.setdefault('playlistend', max(pl_counts) + 1)
 
         ydl = YoutubeDL(params, auto_init=False)
         ydl.add_default_info_extractors()