Make missing test definition fields an error

If the result is not testable (for example, because a description changes often), either pass in a type or a regular expression (a string starting with 're:')

youtube_dl/extractor/arte.py

@@ -302,5 +302,6 @@ class ArteTVConcertIE(ArteTVPlus7IE):
             'ext': 'mp4',
             'title': 'The Notwist im Pariser Konzertclub "Divan du Monde"',
             'upload_date': '20140128',
+            'description': 'md5:486eb08f991552ade77439fe6d82c305',
         },
     }