fix(test): avoid impact of system proxies on urllib test suite by mocking relevant functions

Signed-off-by: Frost Ming <me@frostming.com>

Lib/test/test_urllib.py

@@ -7,6 +7,7 @@
 import email.message
 import io
 import unittest
+import unittest.mock
 from test import support
 from test.support import os_helper
 from test.support import socket_helper
@@ -86,9 +87,15 @@ def fakehttp(self, fakedata, mock_close=False):
         fake_http_class = fakehttp(fakedata, mock_close=mock_close)
         self._connection_class = http.client.HTTPConnection
         http.client.HTTPConnection = fake_http_class
+        # Disable proxies during the test
+        self.getproxies = unittest.mock.patch.object(urllib.request, 'getproxies', return_value={})
+        self.getproxies.start()
+        # Clear cached opener
+        urllib.request.install_opener(None)
 
     def unfakehttp(self):
         http.client.HTTPConnection = self._connection_class
+        self.getproxies.stop()
 
 
 class urlopen_FileTests(unittest.TestCase):

Lib/test/test_urllib2.py

@@ -1380,6 +1380,9 @@ def request(conn, method, url, *pos, **kw):
             # Change response for subsequent connection
             conn.__class__.fakedata = b"HTTP/1.1 200 OK\r\n\r\nHello!"
         http.client.HTTPConnection.request = request
+        with mock.patch('urllib.request.getproxies', return_value={}):
+            # Disable proxy for predictable URL handling
+            urllib.request.install_opener(None)
             fp = urllib.request.urlopen("http://python.org/path")
             self.assertEqual(fp.geturl(), "http://python.org/path?query")
 
@@ -1399,6 +1402,7 @@ def http_open(self, req):
                 )
                 return result
         handler = Handler()
+        with mock.patch('urllib.request.getproxies', return_value={}):
             opener = urllib.request.build_opener(handler)
         tests = (
             (b'/p\xC3\xA5-dansk/', b'/p%C3%A5-dansk/'),

Lib/test/test_urllib2_localnet.py

@@ -6,6 +6,7 @@
 import http.server
 import threading
 import unittest
+import unittest.mock
 import hashlib
 
 from test import support
@@ -336,8 +337,9 @@ def restore_environ(old_environ):
             os.environ.clear()
             os.environ.update(old_environ)
         self.addCleanup(restore_environ, os.environ.copy())
-        os.environ['NO_PROXY'] = ''
+        self._proxy_bypass = unittest.mock.patch('urllib.request.proxy_bypass', return_value=False)
-        os.environ['no_proxy'] = ''
+        self._proxy_bypass.start()
+        self.addCleanup(self._proxy_bypass.stop)
 
         self.digest_auth_handler = DigestAuthHandler()
         self.digest_auth_handler.set_users({self.USER: self.PASSWD})