selenium.common.exceptions.WebDriverException: Message: 'geckodriver' executable needs to be in PATH.

version: selenium==3.0.1
此版本執行需要驅動：geckodriver
可以去網址https://github.com/mozilla/geckodriver/releases 這里下載最新的版本。
然后將文件夾解壓到C:\geckodriver處，再增加在電腦設置環境變量，如下圖所示

然后在創建Firefox的時候設置執行路徑
browser = webdriver.Firefox(executable_path = 'C:\geckodriver\geckodriver.exe')

Traceback (most recent call last):
  File "C:\learnplace\python_webdevelop_testdriver\functional_tests.py", line 10, in <module>
    browser = webdriver.Firefox()
  File "C:\Python27\lib\site-packages\selenium\webdriver\firefox\webdriver.py", line 135, in __init__
    self.service.start()
  File "C:\Python27\lib\site-packages\selenium\webdriver\common\service.py", line 71, in start
    os.path.basename(self.path), self.start_error_message)
selenium.common.exceptions.WebDriverException: Message: 'geckodriver' executable needs to be in PATH. 

Exception AttributeError: "'Service' object has no attribute 'process'" in <bound method Service.__del__ of <selenium.webdriver.firefox.service.Service object at 0x00000000030E7CF8>> ignored

不過此時會出現另外一個異常：

Traceback (most recent call last):
  File "C:\learnplace\python_webdevelop_testdriver\functional_tests.py", line 10, in <module>
    browser = webdriver.Firefox(executable_path = 'C:\geckodriver\geckodriver.exe')
  File "C:\Python27\lib\site-packages\selenium\webdriver\firefox\webdriver.py", line 145, in __init__
    keep_alive=True)
  File "C:\Python27\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 92, in __init__
    self.start_session(desired_capabilities, browser_profile)
  File "C:\Python27\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 179, in start_session
    response = self.execute(Command.NEW_SESSION, capabilities)
  File "C:\Python27\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 236, in execute
    self.error_handler.check_response(response)
  File "C:\Python27\lib\site-packages\selenium\webdriver\remote\errorhandler.py", line 192, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.WebDriverException: Message: Expected browser binary location, but unable to find binary in default location, no 'moz:firefoxOptions.binary' capability provided, and no binary flag set on the command line

需要將binary的瀏覽器路徑添加以下

from selenium import webdriver
from selenium.webdriver.firefox.firefox_binary import FirefoxBinary

# browser = webdriver.Firefox(
# firefox_binary='C:\Program Files (x86)\Mozilla Firefox')
# browser.get('http://localhost:8000')
# assert 'Django' in browser.title
binary = FirefoxBinary(r'C:\Program Files (x86)\Mozilla Firefox\firefox.exe')
browser = webdriver.Firefox(firefox_binary=binary)
browser.get('http://localhost:8000')

不過又出現以下異常。。。

Traceback (most recent call last):
  File "C:\learnplace\python_webdevelop_testdriver\functional_tests.py", line 18, in <module>
    browser = webdriver.Firefox(firefox_binary=binary)
  File "C:\Python27\lib\site-packages\selenium\webdriver\firefox\webdriver.py", line 145, in __init__
    keep_alive=True)
  File "C:\Python27\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 92, in __init__
    self.start_session(desired_capabilities, browser_profile)
  File "C:\Python27\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 179, in start_session
    response = self.execute(Command.NEW_SESSION, capabilities)
  File "C:\Python27\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 236, in execute
    self.error_handler.check_response(response)
  File "C:\Python27\lib\site-packages\selenium\webdriver\remote\errorhandler.py", line 192, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.WebDriverException: Message: Unsupported Marionette protocol version 2, required 3

以上問題只要更新firefox到47版本就可以了。終於解決了。。

使用PhantomJS 無頭瀏覽器

self.browser = webdriver.PhantomJS(executable_path=r'C:\phantomjs\bin\phantomjs.exe')