Simple Pre-Run Executable Example

prerun.py

import unittest
from selenium import webdriver

class Selenium2OnSauce(unittest.TestCase):

    def setUp(self):
        desired_capabilities = webdriver.DesiredCapabilities.CHROME
        #        desired_capabilities['version'] = ''
        desired_capabilities['platform'] = 'VISTA'
        desired_capabilities['name'] = 'Clicking links at jackmoxon.com on Chrome'
        desired_capabilities['prerun'] = URL TO EXACT Executable 
        desired_capabilities['prerun-args'] = '--silent -a -q'


        self.driver = webdriver.Remote(
            desired_capabilities=desired_capabilities,
            command_executor="http://username:API_KEY@ondemand.saucelabs.com:80/wd/hub"
        )
        self.driver.implicitly_wait(30)


    def test_check_links(self):
        ...

    def tearDown(self):
        self.driver.quit()

if __name__ == '__main__':
    unittest.main()