I want to control whether my WebDriver quit but I can't find a method for that. (It seems that in Java there's a way to do it)

from selenium import webdriver
driver = webdriver.Firefox()
driver.quit()
driver # <selenium.webdriver.firefox.webdriver.WebDriver object at 0x108424850>
driver is None # False

I also explored the attributes of WebDriver but I can't locate any specific method to get information on the driver status. Also checking the session id:

driver.session_id # u'7c171019-b24d-5a4d-84ef-9612856af71b'

If you would explore the source code of the python-selenium driver, you would see what the quit() method of the firefox driver is doing:

def quit(self):
    """Quits the driver and close every associated window."""
    try:
        RemoteWebDriver.quit(self)
    except (http_client.BadStatusLine, socket.error):
        # Happens if Firefox shutsdown before we've read the response from
        # the socket.
        pass
    self.binary.kill()
    try:
        shutil.rmtree(self.profile.path)
        if self.profile.tempfolder is not None:
            shutil.rmtree(self.profile.tempfolder)
    except Exception as e:
        print(str(e))

There are things you can rely on here: checking for the profile.path to exist or checking the binary.process status. It could work, but you can also see that there are only "external calls" and there is nothing changing on the python-side that would help you indicate that quit() was called.

In other words, you need to make an external call to check the status:

>>> from selenium.webdriver.remote.command import Command
>>> driver.execute(Command.STATUS)
{u'status': 0, u'name': u'getStatus', u'value': {u'os': {u'version': u'unknown', u'arch': u'x86_64', u'name': u'Darwin'}, u'build': {u'time': u'unknown', u'version': u'unknown', u'revision': u'unknown'}}}
>>> driver.quit()
>>> driver.execute(Command.STATUS)
Traceback (most recent call last):
...
socket.error: [Errno 61] Connection refused

You can put it under the try/except and make a reusable function:

import httplib
import socket

from selenium.webdriver.remote.command import Command

def get_status(driver):
    try:
        driver.execute(Command.STATUS)
        return "Alive"
    except (socket.error, httplib.CannotSendRequest):
        return "Dead"

Usage:

>>> driver = webdriver.Firefox()
>>> get_status(driver)
'Alive'
>>> driver.quit()
>>> get_status(driver)
'Dead'

Another approach would be to make your custom Firefox webdriver and set the session_id to None in quit():

class MyFirefox(webdriver.Firefox):
    def quit(self):
        webdriver.Firefox.quit(self)
        self.session_id = None

Then, you can simply check the session_id value:

>>> driver = MyFirefox()
>>> print driver.session_id
u'69fe0923-0ba1-ee46-8293-2f849c932f43'
>>> driver.quit()
>>> print driver.session_id
None