def test_determine_ext(self):
    self.assertEqual(determine_ext('http://example.com/foo/bar.mp4/?download'), 'mp4')
    self.assertEqual(determine_ext('http://example.com/foo/bar/?download', None), None)
    self.assertEqual(determine_ext('http://example.com/foo/bar.nonext/?download', None), None)
    self.assertEqual(determine_ext('http://example.com/foo/bar/mp4?download', None), None)
    self.assertEqual(determine_ext('http://example.com/foo/bar.m3u8//?download'), 'm3u8')
    self.assertEqual(determine_ext('foobar', None), None)
def test_determine_ext(self):
    self.assertEqual(determine_ext('http://example.com/foo/bar.mp4/?download'), 'mp4')
    self.assertEqual(determine_ext('http://example.com/foo/bar/?download', None), None)
    self.assertEqual(determine_ext('http://example.com/foo/bar.nonext/?download', None), None)
    self.assertEqual(determine_ext('http://example.com/foo/bar/mp4?download', None), None)
    self.assertEqual(determine_ext('http://example.com/foo/bar.m3u8//?download'), 'm3u8')
    self.assertEqual(determine_ext('foobar', None), None)