def load_and_init_from_playback_file(filename, mock_urlopen):
"""Load a gzip json playback file and create YouTube instance."""
pb = load_playback_file(filename)
# Mock the responses to YouTube
mock_url_open_object = mock.Mock()
mock_url_open_object.read.side_effect = [
pb['watch_html'].encode('utf-8'),
pb['js'].encode('utf-8')
]
mock_urlopen.return_value = mock_url_open_object
# Pytest caches this result, so we can speed up the tests
# by causing the object to fetch all the relevant information
# it needs. Previously, this was handled by prefetch_init()
# and descramble(), but this functionality has since been
# deferred
v = YouTube(pb["url"])
v.watch_html
v._vid_info = pb['vid_info']
v.js
v.fmt_streams
return v
