WebDriverException: Message: 'IEDriverServer.exe' executable needs to be in PATH.

详细描述：想用ie浏览器来执行测试用例，按照官方文档http://code.google.com/p/selenium/wiki/IEDriver 的步骤操作后还是报WebDriverException: Message: 'IEDriverServer.exe' executable needs to be in PATH的错，配了系统环境变量重启后也没用。

用下面这种方法设环境变量就可以：

import os
from selenium import webdriver
iedriver = "F:MySoftwareIEDriverServer_x64_3.141.0IEDriverServer.exe"
os.environ["webdriver.ie.driver"] = iedriver
driver =  webdriver.Ie(iedriver)

#driver = webdriver.Ie()
driver.get('https://www.baidu.com/')