title: Error Message: Tried to run command without establishing a connection When running multiple tests with unit test
body: <p>I am having an issue in which all of my tests function correctly when run individually. However, when I try to run all the tests in the file, I get the error Message: Tried to run command without establishing a connection.
  I know the tests work because they run individually, but I need to be able to run all the tests without running them one by one. My code currently looks like this:</p>
  
  <pre><code>import unittest
  from selenium import webdriver
  from selenium.webdriver.common.keys import Keys
  import os
  import time
  from selenium.webdriver.firefox.firefox_binary import FirefoxBinary
  
  gecko = os.path.normpath(os.path.join(os.path.dirname(__file__), 'geckodriver'))
  binary = FirefoxBinary('C:\Program Files (x86)\Mozilla Firefox\Firefox.exe')
  driver = webdriver.Firefox(firefox_binary=binary, executable_path=gecko+'.exe')
  
  class PythonOrgSearch(unittest.TestCase):
  
      def setUp(self):
          self.driver = driver
  
      def test_business_excellence_opens(self):
          driver.get("http://url.network.com")
          self.assertIn("Page Title", driver.title)
  
      def test_home_links(self):
          driver.find_element_by_id('webapps').click()
          self.assertTrue('SPT facilitates the cultural change' in self.driver.page_source)
          time.sleep(1)
          driver.find_element_by_id('complexity').click()
          self.assertTrue('Thank you again' in self.driver.page_source)
          time.sleep(1)
  
      def test_contact_page(self):
          driver.get("http://url.network.com/Home/Contact")
          time.sleep(2)
          driver.find_element_by_id('name').send_keys('name')
          driver.find_element_by_id('ID').send_keys('123456')
          driver.find_element_by_id('email').send_keys('email@email.com')
          driver.find_element_by_id('message').send_keys('Unit testing form')
          driver.find_elements_by_css_selector("button[type='submit']")[0].click()
  
      def tearDown(self):
          self.driver.close()
  
  if __name__ == "__main__":
      unittest.main()
  </code></pre>
  
  <p>To run them one by own I add driver=self.driver and driver.get("url.network.com") at the top of the function</p>