[test] Skip source address tests if the address cannot be bound to (#8900)

Fixes https://github.com/yt-dlp/yt-dlp/issues/8890

Authored by: coletdjnz

test/helper.py

@@ -10,7 +10,7 @@
 import yt_dlp.extractor
 from yt_dlp import YoutubeDL
 from yt_dlp.compat import compat_os_name
-from yt_dlp.utils import preferredencoding, try_call, write_string
+from yt_dlp.utils import preferredencoding, try_call, write_string, find_available_port
 
 if 'pytest' in sys.modules:
     import pytest
@@ -329,3 +329,8 @@ def http_server_port(httpd):
     else:
         sock = httpd.socket
     return sock.getsockname()[1]
+
+
+def verify_address_availability(address):
+    if find_available_port(address) is None:
+        pytest.skip(f'Unable to bind to source address {address} (address may not exist)')

test/test_networking.py

@@ -26,7 +26,7 @@
 from email.message import Message
 from http.cookiejar import CookieJar
 
-from test.helper import FakeYDL, http_server_port
+from test.helper import FakeYDL, http_server_port, verify_address_availability
 from yt_dlp.cookies import YoutubeDLCookieJar
 from yt_dlp.dependencies import brotli, requests, urllib3
 from yt_dlp.networking import (
@@ -538,6 +538,9 @@ def test_timeout(self, handler):
     @pytest.mark.parametrize('handler', ['Urllib', 'Requests'], indirect=True)
     def test_source_address(self, handler):
         source_address = f'127.0.0.{random.randint(5, 255)}'
+        # on some systems these loopback addresses we need for testing may not be available
+        # see: https://github.com/yt-dlp/yt-dlp/issues/8890
+        verify_address_availability(source_address)
         with handler(source_address=source_address) as rh:
             data = validate_and_send(
                 rh, Request(f'http://127.0.0.1:{self.http_port}/source_address')).read().decode()

test/test_socks.py

@@ -25,7 +25,7 @@
     ThreadingTCPServer,
 )
 
-from test.helper import http_server_port
+from test.helper import http_server_port, verify_address_availability
 from yt_dlp.networking import Request
 from yt_dlp.networking.exceptions import ProxyError, TransportError
 from yt_dlp.socks import (
@@ -326,6 +326,7 @@ def test_socks4a_domain_target(self, handler, ctx):
     def test_ipv4_client_source_address(self, handler, ctx):
         with ctx.socks_server(Socks4ProxyHandler) as server_address:
             source_address = f'127.0.0.{random.randint(5, 255)}'
+            verify_address_availability(source_address)
             with handler(proxies={'all': f'socks4://{server_address}'},
                          source_address=source_address) as rh:
                 response = ctx.socks_info_request(rh)
@@ -441,6 +442,7 @@ def test_ipv6_socks5_proxy(self, handler, ctx):
     def test_ipv4_client_source_address(self, handler, ctx):
         with ctx.socks_server(Socks5ProxyHandler) as server_address:
             source_address = f'127.0.0.{random.randint(5, 255)}'
+            verify_address_availability(source_address)
             with handler(proxies={'all': f'socks5://{server_address}'}, source_address=source_address) as rh:
                 response = ctx.socks_info_request(rh)
                 assert response['client_address'][0] == source_address

test/test_websockets.py

@@ -6,6 +6,8 @@
 
 import pytest
 
+from test.helper import verify_address_availability
+
 sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 
 import http.client
@@ -227,6 +229,7 @@ def test_cookies(self, handler):
     @pytest.mark.parametrize('handler', ['Websockets'], indirect=True)
     def test_source_address(self, handler):
         source_address = f'127.0.0.{random.randint(5, 255)}'
+        verify_address_availability(source_address)
         with handler(source_address=source_address) as rh:
             ws = validate_and_send(rh, Request(self.ws_base_url))
             ws.send('source_address')