代码：
from selenium import webdriver
browser = webdriver.Firefox()
browser.get('http://localhost:8000')
assert 'Django' in browser.title报错：
Traceback (most recent call last):
File "/usr/local/lib/python3.5/dist-packages/selenium/webdriver/common/service.py", line 74, in start
stdout=self.log_file, stderr=self.log_file)
File "/usr/lib/python3.5/subprocess.py", line 947, in __init__
restore_signals, start_new_session)
File "/usr/lib/python3.5/subprocess.py", line 1551, in _execute_child
raise child_exception_type(errno_num, err_msg)
FileNotFoundError: [Errno 2] No such file or directory: 'geckodriver'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "functional_test.py", line 2, in <module>
browser = webdriver.Firefox()
File "/usr/local/lib/python3.5/dist-packages/selenium/webdriver/firefox/webdriver.py", line 140, in __init__
self.service.start()
File "/usr/local/lib/python3.5/dist-packages/selenium/webdriver/common/service.py", line 81, in start
os.path.basename(self.path), self.start_error_message)
selenium.common.exceptions.WebDriverException: Message: 'geckodriver' executable needs to be in PATH.
Exception ignored in: <bound method Service.__del__ of <selenium.webdriver.firefox.service.Service object at 0x7f3f272d3ac8>>
Traceback (most recent call last):
File "/usr/local/lib/python3.5/dist-packages/selenium/webdriver/common/service.py", line 173, in __del__
self.stop()
File "/usr/local/lib/python3.5/dist-packages/selenium/webdriver/common/service.py", line 145, in stop
if self.process is None:原因：
未找到firefox浏览器驱动 geckodriver
解决：
下载了Linux的geckodriver
下载地址：https://github.com/mozilla/geckodriver/releases
然后安装
sudo tar zxvf geckodriver-v0.11.1-linux64.tar.gz
sudo mv geckodriver /usr/bin/
sudo chmod +x /usr/bin/geckodriver
再次测试成功
