无法到达WebElement

Question

I'm getting an error the first time I try to get an element. Notice that second time I try that it actually works. This is a debug session:

>>> self.selenium.find_element_by_xpath('//*[@id="add-button"]')
Traceback (most recent call last):
  File "/home/vagrant/.pycharm_helpers/pydev/pydevd_exec2.py", line 3, in Exec
    exec(exp, global_vars, local_vars)
  File "<input>", line 1, in <module>
  File "/vagrant/venv/lib/python3.4/site-packages/selenium/webdriver/remote/webdriver.py", line 232, in find_element_by_xpath
    return self.find_element(by=By.XPATH, value=xpath)
  File "/vagrant/venv/lib/python3.4/site-packages/selenium/webdriver/remote/webdriver.py", line 664, in find_element
    {'using': by, 'value': value})['value']
  File "/vagrant/venv/lib/python3.4/site-packages/selenium/webdriver/remote/webdriver.py", line 173, in execute
    response = self.command_executor.execute(driver_command, params)
  File "/vagrant/venv/lib/python3.4/site-packages/selenium/webdriver/remote/remote_connection.py", line 349, in execute
    return self._request(command_info[0], url, body=data)
  File "/vagrant/venv/lib/python3.4/site-packages/selenium/webdriver/remote/remote_connection.py", line 380, in _request
    resp = self._conn.getresponse()
  File "/usr/lib/python3.4/http/client.py", line 1147, in getresponse
    response.begin()
  File "/usr/lib/python3.4/http/client.py", line 351, in begin
    version, status, reason = self._read_status()
  File "/usr/lib/python3.4/http/client.py", line 321, in _read_status
    raise BadStatusLine(line)
http.client.BadStatusLine: ''
>>> self.selenium.find_element_by_xpath('//*[@id="add-button"]')
<selenium.webdriver.remote.webelement.WebElement object at 0x7f90ab074400>

And this is the code:

from selenium.webdriver.firefox.webdriver import WebDriver
from django.contrib.staticfiles.testing import StaticLiveServerTestCase
from xvfbwrapper import Xvfb

class UIPropertyTestCase(StaticLiveServerTestCase):
    fixtures = ['properties']

    @classmethod
    def setUpClass(cls):
        cls.vdisplay = Xvfb()
        cls.vdisplay.start()
        cls.selenium = WebDriver()
        cls.selenium.implicitly_wait(10)
        super(UIPropertyTestCase, cls).setUpClass()

    @classmethod
    def tearDownClass(cls):
        cls.selenium.quit()
        cls.vdisplay.stop()
        super(UIPropertyTestCase, cls).tearDownClass()

    def test_add_property(self):
        self.selenium.get('{0}{1}'.format(self.live_server_url, '/#/app/properties'))
        self.selenium.find_element_by_xpath('//*[@id="add-button"]').click()

        self.selenium.get('{0}{1}'.format(self.live_server_url, '/#/app/properties'))
        count = len(self.selenium.find_elements_by_xpath('//*[@id="data"]/tbody/tr'))
        self.assertEqual(count, 3)

Found this comment on /usr/lib/python3.4/http/client.py:319:

Presumably, the server closed the connection before sending a valid response.

Additional info:

• OS: Ubuntu 14.04.2 LTS
• Python: 3.4.0
• Django: 1.7.6
• selenium: 2.45.0
• Firefox: 36.0.4

Any idea what could I be missing?

Answer 1

As said when something goes strange with Selenium it is usually good idea to update it and also update firefox.

In your case are you sure that element was actually loaded? I can see implicitly wait method but loading time may vary so it might be not enough.

You can start by increasing implicitly_wait time and try once again.