[py] add warning if people set w3c to false as it may break their tests

Author: AutomatedTester

py/selenium/webdriver/chromium/options.py

@@ -17,6 +17,7 @@
 
 import base64
 import os
+import warnings
 from typing import List, NoReturn, Union
 
 from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
@@ -129,6 +130,8 @@ def add_experimental_option(self, name: str, value: Union[str, int, dict, List[s
           name: The experimental option name.
           value: The option value.
         """
+        if name.lower() == "w3c" and (value == "false" or value == False):
+            warnings.warn(UserWarning("Manipulating `w3c` setting can have unintended consequences."))
         self._experimental_options[name] = value
 
     @property

py/test/unit/selenium/webdriver/chrome/chrome_options_tests.py

@@ -161,3 +161,8 @@ def test_enables_chrome_mobile(options):
     options.enable_mobile()
     result_caps = options.to_capabilities()
     assert result_caps["goog:chromeOptions"]["androidPackage"] == "com.android.chrome"
+
+
+def test_set_w3c_false(options):
+    with pytest.warns(UserWarning):
+        options.add_experimental_option("w3c", False)