How can I get Selenium WebDriver to wait until <dd> element contains data before proceeding?
<p>Am trying to automate feeding a url to Pingdom's Website Speed Test (see <a href="http://tools.pingdom.com/fpt/" rel="nofollow">http://tools.pingdom.com/fpt/</a>) and then extract and print the result of that test. </p>

<p>I have written some code but I can't figure out how to get the data out of the 'Perf. grade'  element. </p>

<p>It seems that the element exists before the test is run (which I guess is run server-side?) but is empty. Then once the test has finished the  element is populated with the value. </p>

<p>How can I get Selenium to wait until this value is populated before attempting to print it?</p>

<p>Here is my code:</p>

<pre><code>import datetime
from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

# Pingdom Website Speed Test
for i in range(0, 1):

    # Initialises chromedriver
    driver = webdriver.Chrome(executable_path=r'C:\Users\Desktop\Python\chromedriver\chromedriver.exe')

    # Opens Pingdom homepage
    driver.get('http://tools.pingdom.com/fpt/')

    # Looks for search box, enters 'http://www.url.com/' and submits it
    pingdom_url_element = driver.find_element_by_id('urlinput')
    pingdom_url_element.send_keys('http://www.url.com/')
    pingdom_test_button_element = "//button[@tabindex='2']"
    driver.find_element_by_xpath(pingdom_test_button_element).click()

    # Waits until page has loaded then looks for attribute containing the report score's value and returns the value
    pingdom_performance_result = WebDriverWait(driver, 60).until(EC.presence_of_element_located((By.XPATH, "//div[@id='rt_sumright']/dl[@class='last']/dd[1]")))

    print('Pingdom score:')
    print(datetime.datetime.now().strftime("%d-%m-%Y %H:%M:%S"), "---", pingdom_performance_result.text)

    driver.close()

    i += 1
</code></pre>