bitbake: toaster/tests: fix chrome argument syntax and wait for driver exit

The chrome driver sometimes fails with a page crash for a full suite
of tests, pointing to a failure in the setup of the driver due to
resource limitations.
To mitigate these crashes, add a wait between driver driven tests to
ensure resources are freed.

(Bitbake rev: 8f998e27aae694c16f788aac12558621089d0839)

Signed-off-by: Alexander Lussier-Cullen <alexander.lussier-cullen@savoirfairelinux.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/toaster/tests/browser/selenium_helpers_base.py

@@ -36,7 +36,7 @@ def create_selenium_driver(cls,browser='chrome'):
 
     if browser == 'chrome':
         options = webdriver.ChromeOptions()
-        options.add_argument('headless')
+        options.add_argument('--headless')
         options.add_argument('--disable-infobars')
         options.add_argument('--disable-dev-shm-usage')
         options.add_argument('--no-sandbox')
@@ -166,6 +166,8 @@ class SeleniumTestCaseBase(unittest.TestCase):
         """ Clean up webdriver driver """
 
         cls.driver.quit()
+        # Allow driver resources to be properly freed before proceeding with further tests
+        time.sleep(5)
         super(SeleniumTestCaseBase, cls).tearDownClass()
 
     def get(self, url):