Fix #30220 -- Headless browser mode for selenium test

Both Chrome and Firefox support a new headless mode now. Besides
being faster, it also is more reliable as well as convenient since
there are no windows popping up.

django/test/selenium.py

@@ -17,6 +17,8 @@ class SeleniumTestCaseBase(type(LiveServerTestCase)):
     external_host = None
     # Sentinel value to differentiate browser-specific instances.
     browser = None
+    # Run browsers in headless mode
+    headless = False
 
     def __new__(cls, name, bases, attrs):
         """
@@ -62,19 +64,32 @@ def __new__(cls, name, bases, attrs):
     def import_webdriver(cls, browser):
         return import_string("selenium.webdriver.%s.webdriver.WebDriver" % browser)
 
+    @classmethod
+    def import_options(cls, browser):
+        return import_string("selenium.webdriver.%s.options.Options" % browser)
+
     @classmethod
     def get_capability(cls, browser):
         from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
         return getattr(DesiredCapabilities, browser.upper())
 
+    def create_options(self):
+        options = self.import_options(self.browser)()
+        if self.headless:
+            try:
+                options.headless = True
+            except AttributeError:
+                pass  # only Chrome and Firefox support the headless mode
+        return options
+
     def create_webdriver(self):
         if self.selenium_hub:
             from selenium import webdriver
             return webdriver.Remote(
                 command_executor=self.selenium_hub,
                 desired_capabilities=self.get_capability(self.browser),
             )
-        return self.import_webdriver(self.browser)()
+        return self.import_webdriver(self.browser)(options=self.create_options())
 
 
 @tag('selenium')

docs/internals/contributing/writing-code/unit-tests.txt

@@ -210,6 +210,10 @@ See the `selenium.webdriver`_ package for the list of available browsers.
 Specifying ``--selenium`` automatically sets ``--tags=selenium`` to run only
 the tests that require selenium.
 
+Some browsers such as Chrome and Firefox support a headless mode, which can be
+faster and more stable in conjunction with Selenium tests. Add the
+``--selenium-headless`` option to enable the headless mode.
+
 .. _selenium.webdriver: https://github.com/SeleniumHQ/selenium/tree/master/py/selenium/webdriver
 
 .. _running-unit-tests-dependencies:

tests/runtests.py

@@ -437,6 +437,10 @@ def paired_tests(paired_test, options, test_labels, parallel):
         '--selenium', action=ActionSelenium, metavar='BROWSERS',
         help='A comma-separated list of browsers to run the Selenium tests against.',
     )
+    parser.add_argument(
+        '--selenium-headless', action='store_true',
+        help='Run selenium tests in headless mode, if the browser support the option.'
+    )
     parser.add_argument(
         '--selenium-hub',
         help='A URL for a selenium hub instance to use in combination with --selenium.',
@@ -489,6 +493,8 @@ def paired_tests(paired_test, options, test_labels, parallel):
         if options.selenium_hub:
             SeleniumTestCaseBase.selenium_hub = options.selenium_hub
             SeleniumTestCaseBase.external_host = options.external_host
+        if options.selenium_headless:
+            SeleniumTestCaseBase.headless = True
         SeleniumTestCaseBase.browsers = options.selenium
 
     if options.bisect: