add capability to suppress expected warnings in tests

test/helper.py

@@ -1,6 +1,8 @@
 import io
 import json
 import os.path
+import re
+import types
 
 import youtube_dl.extractor
 from youtube_dl import YoutubeDL, YoutubeDLHandler
@@ -32,6 +34,19 @@ class FakeYDL(YoutubeDL):
         raise Exception(s)
     def download(self, x):
         self.result.append(x)
+    # def expect_warning(self, regex):
+    #     # Silence an expected warning matching a regex
+    #     def report_warning(self, message):
+    #         if re.match(regex, message): return
+    #         super(FakeYDL, self).report_warning(regex)
+    #     self.report_warning = types.MethodType(report_warning, self)
+    def expect_warning(self, regex):
+        # Silence an expected warning matching a regex
+        old_report_warning = self.report_warning
+        def report_warning(self, message):
+            if re.match(regex, message): return
+            old_report_warning(message)
+        self.report_warning = types.MethodType(report_warning, self)
 
 def get_testcases():
     for ie in youtube_dl.extractor.gen_extractors():