from selenium import webdriver

from selenium.webdriver.common.action_chains import ActionChains

from selenium.common.exceptions import UnexpectedAlertPresentException

from time import sleep

driver= webdriver.Ie()

driver.get('https://www.helloweba.net/demo/2017/unlock/')

driver.implicitly_wait(5)

dragger = driver.find_elements_by_class_name('slide-to-unlock-handle')[0]  #错误为：find_element_by_class_name

action = ActionChains(driver)

action.click_and_hold(dragger).perform()   #鼠标左键按住不放

for index in range(200):

    try:

        action.move_by_offset(2,0).perform()   #平行移动鼠标

    except UnexpectedAlertPresentException:

        break

    action.reset_actions()

    sleep(0.1)    #等待停顿时间

sucess_text = driver.switch_to.alert.text

print(sucess_text)    #打印警告框提示

sleep(5)

driver.quit()