Fixes 4784 - Improve error reporting in updateMalwareDomainsList and add tests

sitescripts/subscriptions/bin/updateMalwareDomainsList.py

 # This file is part of the Adblock Plus web scripts,
 # Copyright (C) 2006-2016 Eyeo GmbH
 #
 # Adblock Plus is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 3 as
 # published by the Free Software Foundation.
 #
 # Adblock Plus is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
@@ skipping 23 matching lines @@
 !'''
 
 MALWAREDOMAINS_PATH = '/files/justdomains.zip'
 
 
 def try_mirror(mirror):
     url = mirror + MALWAREDOMAINS_PATH
     try:
         with contextlib.closing(urllib2.urlopen(url)) as response:
             return None, response.read()
+    except urllib2.HTTPError as exc:
+        exc.close()
     except urllib2.URLError as exc:
-        error_message = 'Failed to fetch {}: {}'.format(url, exc)
-        if hasattr(exc, 'close'):

[Vasily Kuznetsov, 2017/01/19 16:34:08]

I tried to do it with two separate except clauses but that creates too much
repetition. How about a duck typish check instead!

[Sebastian Noack, 2017/01/19 17:13:33]

I don't see how that creates any duplication.

  try:
      ...
  except urllib2.HTTPError as e:
      e.close()
  except urllib2.URLError as e:
      pass
  return 'Failed to fetch {}: {}'.format(url, e), None

[Vasily Kuznetsov, 2017/01/20 13:44:49]

Yeah, this is better. Thanks.

-            exc.close()
-        return error_message, None
+        pass
+    return 'Failed to fetch {}: {}'.format(url, exc), None
 
 
 def main():
     config = get_config()
     section = 'subscriptionDownloads'
     repository = config.get(section, 'malwaredomains_repository')
     mirrors = config.get(section, 'malwaredomains_mirrors').split()
 
     tempdir = tempfile.mkdtemp(prefix='malwaredomains')
     try:
@@ skipping 26 matching lines @@
 
         if subprocess.check_output(['hg', 'stat', '-R', tempdir]) != '':
             subprocess.check_call(['hg', '-q', 'commit', '-R', tempdir, '-A', '-u', 'hgbot', '-m', 'Updated malwaredomains.com data'])
             subprocess.check_call(['hg', '-q', 'push', '-R', tempdir])
     finally:
         shutil.rmtree(tempdir, ignore_errors=True)
 
 
 if __name__ == '__main__':
     main()