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Validating YouTube Signature Processing in youtube-dl

This test suite validates YouTube’s signature verification and player functionality in youtube-dl. It focuses on testing signature extraction, transformation, and validation across different YouTube player versions and implementations.

Test Coverage Overview

The test suite covers signature verification for both regular and n-type signatures across multiple YouTube player versions.

Key areas tested include:

Player info extraction from various URL formats
Signature transformation validation
Edge cases with different player versions and configurations
Integration with YouTube’s player JavaScript code

Implementation Analysis

The testing approach uses unittest to verify signature processing against known valid signatures.

Key implementation patterns include:

Dynamic test generation using test factories
JavaScript code interpretation and execution
URL pattern matching and validation
File-based test data management

Technical Details

Testing tools and configuration:

Python unittest framework
Custom JSInterpreter for JavaScript execution
Local file caching of player JavaScript
URL pattern matching with regex
Dynamic test case generation

Best Practices Demonstrated

The test suite demonstrates several testing best practices including test isolation, data-driven test generation, and comprehensive coverage of edge cases.

Notable practices include:

Separation of test data from test logic
Automated test case generation
Proper test setup and teardown
Comprehensive validation of different player versions

ytdl-org/youtube-dl

test/test_youtube_signature.py

            
#!/usr/bin/env python
# coding: utf-8

from __future__ import unicode_literals

# Allow direct execution
import os
import sys
import unittest
sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))

import re
import string

from youtube_dl.compat import (
    compat_contextlib_suppress,
    compat_open as open,
    compat_str,
    compat_urlretrieve,
)

from test.helper import FakeYDL
from youtube_dl.extractor import YoutubeIE
from youtube_dl.jsinterp import JSInterpreter

_SIG_TESTS = [
    (
        'https://s.ytimg.com/yts/jsbin/html5player-vflHOr_nV.js',
        86,
        '>=<;:/.-[+*)(\'&%$#"!ZYX0VUTSRQPONMLKJIHGFEDCBA\\yxwvutsrqponmlkjihgfedcba987654321',
    ),
    (
        'https://s.ytimg.com/yts/jsbin/html5player-vfldJ8xgI.js',
        85,
        '3456789a0cdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRS[UVWXYZ!"#$%&\'()*+,-./:;<=>?@',
    ),
    (
        'https://s.ytimg.com/yts/jsbin/html5player-vfle-mVwz.js',
        90,
        ']\\[@?>=<;:/.-,+*)(\'&%$#"hZYXWVUTSRQPONMLKJIHGFEDCBAzyxwvutsrqponmlkjiagfedcb39876',
    ),
    (
        'https://s.ytimg.com/yts/jsbin/html5player-en_US-vfl0Cbn9e.js',
        84,
        'O1I3456789abcde0ghijklmnopqrstuvwxyzABCDEFGHfJKLMN2PQRSTUVW@YZ!"#$%&\'()*+,-./:;<=',
    ),
    (
        'https://s.ytimg.com/yts/jsbin/html5player-en_US-vflXGBaUN.js',
        '2ACFC7A61CA478CD21425E5A57EBD73DDC78E22A.2094302436B2D377D14A3BBA23022D023B8BC25AA',
        'A52CB8B320D22032ABB3A41D773D2B6342034902.A22E87CDD37DBE75A5E52412DC874AC16A7CFCA2',
    ),
    (
        'https://s.ytimg.com/yts/jsbin/html5player-en_US-vflBb0OQx.js',
        84,
        '123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQ0STUVWXYZ!"#$%&\'()*+,@./:;<=>',
    ),
    (
        'https://s.ytimg.com/yts/jsbin/html5player-en_US-vfl9FYC6l.js',
        83,
        '123456789abcdefghijklmnopqr0tuvwxyzABCDETGHIJKLMNOPQRS>UVWXYZ!"#$%&\'()*+,-./:;<=F',
    ),
    (
        'https://s.ytimg.com/yts/jsbin/html5player-en_US-vflCGk6yw/html5player.js',
        '4646B5181C6C3020DF1D9C7FCFEA.AD80ABF70C39BD369CCCAE780AFBB98FA6B6CB42766249D9488C288',
        '82C8849D94266724DC6B6AF89BBFA087EACCD963.B93C07FBA084ACAEFCF7C9D1FD0203C6C1815B6B',
    ),
    (
        'https://s.ytimg.com/yts/jsbin/html5player-en_US-vflKjOTVq/html5player.js',
        '312AA52209E3623129A412D56A40F11CB0AF14AE.3EE09501CB14E3BCDC3B2AE808BF3F1D14E7FBF12',
        '112AA5220913623229A412D56A40F11CB0AF14AE.3EE0950FCB14EEBCDC3B2AE808BF331D14E7FBF3',
    ),
    (
        'https://www.youtube.com/s/player/6ed0d907/player_ias.vflset/en_US/base.js',
        '2aq0aqSyOoJXtK73m-uME_jv7-pT15gOFC02RFkGMqWpzEICs69VdbwQ0LDp1v7j8xx92efCJlYFYb1sUkkBSPOlPmXgIARw8JQ0qOAOAA',
        'AOq0QJ8wRAIgXmPlOPSBkkUs1bYFYlJCfe29xx8j7v1pDL2QwbdV96sCIEzpWqMGkFR20CFOg51Tp-7vj_EMu-m37KtXJoOySqa0',
    ),
    (
        'https://www.youtube.com/s/player/3bb1f723/player_ias.vflset/en_US/base.js',
        '2aq0aqSyOoJXtK73m-uME_jv7-pT15gOFC02RFkGMqWpzEICs69VdbwQ0LDp1v7j8xx92efCJlYFYb1sUkkBSPOlPmXgIARw8JQ0qOAOAA',
        'MyOSJXtKI3m-uME_jv7-pT12gOFC02RFkGoqWpzE0Cs69VdbwQ0LDp1v7j8xx92efCJlYFYb1sUkkBSPOlPmXgIARw8JQ0qOAOAA',
    ),
    (
        'https://www.youtube.com/s/player/2f1832d2/player_ias.vflset/en_US/base.js',
        '2aq0aqSyOoJXtK73m-uME_jv7-pT15gOFC02RFkGMqWpzEICs69VdbwQ0LDp1v7j8xx92efCJlYFYb1sUkkBSPOlPmXgIARw8JQ0qOAOAA',
        '0QJ8wRAIgXmPlOPSBkkUs1bYFYlJCfe29xxAj7v1pDL0QwbdV96sCIEzpWqMGkFR20CFOg51Tp-7vj_EMu-m37KtXJ2OySqa0q',
    ),
]

_NSIG_TESTS = [
    (
        'https://www.youtube.com/s/player/7862ca1f/player_ias.vflset/en_US/base.js',
        'X_LCxVDjAavgE5t', 'yxJ1dM6iz5ogUg',
    ),
    (
        'https://www.youtube.com/s/player/9216d1f7/player_ias.vflset/en_US/base.js',
        'SLp9F5bwjAdhE9F-', 'gWnb9IK2DJ8Q1w',
    ),
    (
        'https://www.youtube.com/s/player/f8cb7a3b/player_ias.vflset/en_US/base.js',
        'oBo2h5euWy6osrUt', 'ivXHpm7qJjJN',
    ),
    (
        'https://www.youtube.com/s/player/2dfe380c/player_ias.vflset/en_US/base.js',
        'oBo2h5euWy6osrUt', '3DIBbn3qdQ',
    ),
    (
        'https://www.youtube.com/s/player/f1ca6900/player_ias.vflset/en_US/base.js',
        'cu3wyu6LQn2hse', 'jvxetvmlI9AN9Q',
    ),
    (
        'https://www.youtube.com/s/player/8040e515/player_ias.vflset/en_US/base.js',
        'wvOFaY-yjgDuIEg5', 'HkfBFDHmgw4rsw',
    ),
    (
        'https://www.youtube.com/s/player/e06dea74/player_ias.vflset/en_US/base.js',
        'AiuodmaDDYw8d3y4bf', 'ankd8eza2T6Qmw',
    ),
    (
        'https://www.youtube.com/s/player/5dd88d1d/player-plasma-ias-phone-en_US.vflset/base.js',
        'kSxKFLeqzv_ZyHSAt', 'n8gS8oRlHOxPFA',
    ),
    (
        'https://www.youtube.com/s/player/324f67b9/player_ias.vflset/en_US/base.js',
        'xdftNy7dh9QGnhW', '22qLGxrmX8F1rA',
    ),
    (
        'https://www.youtube.com/s/player/4c3f79c5/player_ias.vflset/en_US/base.js',
        'TDCstCG66tEAO5pR9o', 'dbxNtZ14c-yWyw',
    ),
    (
        'https://www.youtube.com/s/player/c81bbb4a/player_ias.vflset/en_US/base.js',
        'gre3EcLurNY2vqp94', 'Z9DfGxWP115WTg',
    ),
    (
        'https://www.youtube.com/s/player/1f7d5369/player_ias.vflset/en_US/base.js',
        'batNX7sYqIJdkJ', 'IhOkL_zxbkOZBw',
    ),
    (
        'https://www.youtube.com/s/player/009f1d77/player_ias.vflset/en_US/base.js',
        '5dwFHw8aFWQUQtffRq', 'audescmLUzI3jw',
    ),
    (
        'https://www.youtube.com/s/player/dc0c6770/player_ias.vflset/en_US/base.js',
        '5EHDMgYLV6HPGk_Mu-kk', 'n9lUJLHbxUI0GQ',
    ),
    (
        'https://www.youtube.com/s/player/c2199353/player_ias.vflset/en_US/base.js',
        '5EHDMgYLV6HPGk_Mu-kk', 'AD5rgS85EkrE7',
    ),
    (
        'https://www.youtube.com/s/player/113ca41c/player_ias.vflset/en_US/base.js',
        'cgYl-tlYkhjT7A', 'hI7BBr2zUgcmMg',
    ),
    (
        'https://www.youtube.com/s/player/c57c113c/player_ias.vflset/en_US/base.js',
        '-Txvy6bT5R6LqgnQNx', 'dcklJCnRUHbgSg',
    ),
    (
        'https://www.youtube.com/s/player/5a3b6271/player_ias.vflset/en_US/base.js',
        'B2j7f_UPT4rfje85Lu_e', 'm5DmNymaGQ5RdQ',
    ),
    (
        'https://www.youtube.com/s/player/7a062b77/player_ias.vflset/en_US/base.js',
        'NRcE3y3mVtm_cV-W', 'VbsCYUATvqlt5w',
    ),
    (
        'https://www.youtube.com/s/player/dac945fd/player_ias.vflset/en_US/base.js',
        'o8BkRxXhuYsBCWi6RplPdP', '3Lx32v_hmzTm6A',
    ),
    (
        'https://www.youtube.com/s/player/6f20102c/player_ias.vflset/en_US/base.js',
        'lE8DhoDmKqnmJJ', 'pJTTX6XyJP2BYw',
    ),
    (
        'https://www.youtube.com/s/player/cfa9e7cb/player_ias.vflset/en_US/base.js',
        'qO0NiMtYQ7TeJnfFG2', 'k9cuJDHNS5O7kQ',
    ),
    (
        'https://www.youtube.com/s/player/8c7583ff/player_ias.vflset/en_US/base.js',
        '1wWCVpRR96eAmMI87L', 'KSkWAVv1ZQxC3A',
    ),
    (
        'https://www.youtube.com/s/player/b7910ca8/player_ias.vflset/en_US/base.js',
        '_hXMCwMt9qE310D', 'LoZMgkkofRMCZQ',
    ),
    (
        'https://www.youtube.com/s/player/590f65a6/player_ias.vflset/en_US/base.js',
        '1tm7-g_A9zsI8_Lay_', 'xI4Vem4Put_rOg',
    ),
    (
        'https://www.youtube.com/s/player/b22ef6e7/player_ias.vflset/en_US/base.js',
        'b6HcntHGkvBLk_FRf', 'kNPW6A7FyP2l8A',
    ),
    (
        'https://www.youtube.com/s/player/3400486c/player_ias.vflset/en_US/base.js',
        'lL46g3XifCKUZn1Xfw', 'z767lhet6V2Skl',
    ),
    (
        'https://www.youtube.com/s/player/5604538d/player_ias.vflset/en_US/base.js',
        '7X-he4jjvMx7BCX', 'sViSydX8IHtdWA',
    ),
    (
        'https://www.youtube.com/s/player/20dfca59/player_ias.vflset/en_US/base.js',
        '-fLCxedkAk4LUTK2', 'O8kfRq1y1eyHGw',
    ),
    (
        'https://www.youtube.com/s/player/b12cc44b/player_ias.vflset/en_US/base.js',
        'keLa5R2U00sR9SQK', 'N1OGyujjEwMnLw',
    ),
    (
        'https://www.youtube.com/s/player/3bb1f723/player_ias.vflset/en_US/base.js',
        'gK15nzVyaXE9RsMP3z', 'ZFFWFLPWx9DEgQ',
    ),
    (
        'https://www.youtube.com/s/player/f8f53e1a/player_ias.vflset/en_US/base.js',
        'VTQOUOv0mCIeJ7i8kZB', 'kcfD8wy0sNLyNQ',
    ),
    (
        'https://www.youtube.com/s/player/2f1832d2/player_ias.vflset/en_US/base.js',
        'YWt1qdbe8SAfkoPHW5d', 'RrRjWQOJmBiP',
    ),
]


class TestPlayerInfo(unittest.TestCase):
    def test_youtube_extract_player_info(self):
        PLAYER_URLS = (
            ('https://www.youtube.com/s/player/4c3f79c5/player_ias.vflset/en_US/base.js', '4c3f79c5'),
            ('https://www.youtube.com/s/player/64dddad9/player_ias.vflset/en_US/base.js', '64dddad9'),
            ('https://www.youtube.com/s/player/64dddad9/player_ias.vflset/fr_FR/base.js', '64dddad9'),
            ('https://www.youtube.com/s/player/64dddad9/player-plasma-ias-phone-en_US.vflset/base.js', '64dddad9'),
            ('https://www.youtube.com/s/player/64dddad9/player-plasma-ias-phone-de_DE.vflset/base.js', '64dddad9'),
            ('https://www.youtube.com/s/player/64dddad9/player-plasma-ias-tablet-en_US.vflset/base.js', '64dddad9'),
            # obsolete
            ('https://www.youtube.com/yts/jsbin/player_ias-vfle4-e03/en_US/base.js', 'vfle4-e03'),
            ('https://www.youtube.com/yts/jsbin/player_ias-vfl49f_g4/en_US/base.js', 'vfl49f_g4'),
            ('https://www.youtube.com/yts/jsbin/player_ias-vflCPQUIL/en_US/base.js', 'vflCPQUIL'),
            ('https://www.youtube.com/yts/jsbin/player-vflzQZbt7/en_US/base.js', 'vflzQZbt7'),
            ('https://www.youtube.com/yts/jsbin/player-en_US-vflaxXRn1/base.js', 'vflaxXRn1'),
            ('https://s.ytimg.com/yts/jsbin/html5player-en_US-vflXGBaUN.js', 'vflXGBaUN'),
            ('https://s.ytimg.com/yts/jsbin/html5player-en_US-vflKjOTVq/html5player.js', 'vflKjOTVq'),
        )
        for player_url, expected_player_id in PLAYER_URLS:
            player_id = YoutubeIE._extract_player_info(player_url)
            self.assertEqual(player_id, expected_player_id)


class TestSignature(unittest.TestCase):
    def setUp(self):
        TEST_DIR = os.path.dirname(os.path.abspath(__file__))
        self.TESTDATA_DIR = os.path.join(TEST_DIR, 'testdata/sigs')
        if not os.path.exists(self.TESTDATA_DIR):
            os.mkdir(self.TESTDATA_DIR)

    def tearDown(self):
        with compat_contextlib_suppress(OSError):
            for f in os.listdir(self.TESTDATA_DIR):
                os.remove(f)


def t_factory(name, sig_func, url_pattern):
    def make_tfunc(url, sig_input, expected_sig):
        m = url_pattern.match(url)
        assert m, '%r should follow URL format' % url
        test_id = m.group('id')

        def test_func(self):
            basename = 'player-{0}-{1}.js'.format(name, test_id)
            fn = os.path.join(self.TESTDATA_DIR, basename)

            if not os.path.exists(fn):
                compat_urlretrieve(url, fn)
            with open(fn, encoding='utf-8') as testf:
                jscode = testf.read()
            self.assertEqual(sig_func(jscode, sig_input), expected_sig)

        test_func.__name__ = str('test_{0}_js_{1}'.format(name, test_id))
        setattr(TestSignature, test_func.__name__, test_func)
    return make_tfunc


def signature(jscode, sig_input):
    func = YoutubeIE(FakeYDL())._parse_sig_js(jscode)
    src_sig = (
        compat_str(string.printable[:sig_input])
        if isinstance(sig_input, int) else sig_input)
    return func(src_sig)


def n_sig(jscode, sig_input):
    funcname = YoutubeIE(FakeYDL())._extract_n_function_name(jscode)
    return JSInterpreter(jscode).call_function(
        funcname, sig_input, _ytdl_do_not_return=sig_input)


make_sig_test = t_factory(
    'signature', signature, re.compile(r'.*(?:-|/player/)(?P<id>[a-zA-Z0-9_-]+)(?:/.+\.js|(?:/watch_as3|/html5player)?\.[a-z]+)$'))
for test_spec in _SIG_TESTS:
    make_sig_test(*test_spec)

make_nsig_test = t_factory(
    'nsig', n_sig, re.compile(r'.+/player/(?P<id>[a-zA-Z0-9_-]+)/.+.js$'))
for test_spec in _NSIG_TESTS:
    make_nsig_test(*test_spec)


if __name__ == '__main__':
    unittest.main()