如何用selenium webdriver 捕获js error

# -*- coding:utf8 -*-

import unittest
from selenium import webdriver
from selenium.webdriver.common.desired_capabilities import DesiredCapabilities


class CaptureJSError(unittest.TestCase):

    @classmethod
    def setUp(self):
        self.driver = webdriver.Remote(‘http://yourseleniumgrid:4444/wd/hub‘,
                                       desired_capabilities=DesiredCapabilities.FIREFOX)
    def test_search_in_python_org(self):
        driver = self.driver
        driver.get("http://foopagewitherr:80")
        logs = driver.get_log(‘browser‘)
        for log in logs:
            if log[‘level‘] == ‘SEVERE‘:
                print log
                # output is {u‘timestamp‘: 1474618002360, u‘message‘: u‘TypeError: $(...).ready_ is not a function‘, u‘level‘: u‘SEVERE‘}

    @classmethod
    def tearDown(self):
        self.driver.close()


if __name__ == "__main__":
    unittest.main()