How to correctly pass basic auth (every click) usi

I am running some unittests with Selenium Webdriver.

I have an entire test that runs successfully using webdriver.Firefox(), here is the setup:

def setUp(self):
    self.driver = webdriver.Firefox()
    self.driver.implicitly_wait(30)
    self.base_url = "http://www.nike.com"
    self.verificationErrors = []
    self.accept_next_alert = True

The test runs successfully, however I have to manually enter in basic auth multiple times for the test to keep moving forward.

In an attempt to bypass basic auth and have the entire test truly automated, I have switched from Firefox to phantomjs, as it sounds like you can pass in Basic Auth with each click()

Here is my setup after switching to phantomjs:

def setUp(self):
    dcap = dict(DesiredCapabilities.PHANTOMJS)
    dcap["phantoms.page.settings.userName"] = ("testuser")
    dcap["phantoms.page.settings.userPassword"] = ("testpass")
    self.driver = webdriver.PhantomJS(desired_capabilities=dcap, service_args=['--ignore-ssl-errors=true'])
    self.driver.implicitly_wait(30)
    self.base_url = "http://www.nike.com
    self.verificationErrors = []
    self.accept_next_alert = True

But I get the following error:

NoSuchElementException: Message: {"errorMessage":"Unable to find
element with xpath '(//button[@type='button'])[2]'","request":
{"headers":{"Accept":"application/json","Accept-Encoding":"identity",
"Connection":"close","Content-Length":"113","Content- Type":"application/json;charset=UTF-8",
"Host":"127.0.0.1:58025","UserAgent":"Pythonurllib/2.7"},"httpVersion":"1.1",
"method":"POST","post":"{\"using\": \"xpath\", \"sessionId\": \"c2fa02e0-1df0-11e6-a2ad-c325e56df16d\",
\"value\": \"(//button[@type='button'][2]\"}","url":"/element","urlParsed":
{"anchor":"","query":"","file":"element","directory":"/","path":"/element","relative":"/element","port":"","host":"",
"password":"","user":"","userInfo":"","authority":"","protocol":"","source":"/element","queryKey":{},"chunks":    
["element"]},"urlOriginal":"/session/c2fa02e0-1df0-11e6-a2ad-c325e56df16d/element"}}

I am not sure if this error is just a difference between phantomjs and firefox, or if I'm just passing auth incorrectly.

Here is the way to define the basic authentication token in the headers with PhantomJS and Selenium:

from selenium import webdriver
from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
import base64

authentication_token = "Basic " + base64.b64encode(b'username:password')

capa = DesiredCapabilities.PHANTOMJS
capa['phantomjs.page.customHeaders.Authorization'] = authentication_token
driver = webdriver.PhantomJS(desired_capabilities=capa)

driver.get("http://...")