CSS Selector using ':contains' fails with `invalid element state: Failed to execute 'querySelector' on 'Document: is not a valid selector'`

Question

I'm new to Selenium. I'm using it with Python. I'm trying to use a CSS Selector with :contains but failed so far.

• On Chrome, the selector is rejected with 'a:contains("mail")' is not a valid selector
• On Firefox, it selects nothing and get timed out

Please help to point out what I'm doing wrong.

The snippet for Chrome is as follows:

from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

browser = webdriver.Chrome('/path/to/chromedriver')

browser.get('https://www.google.com/')

try:
    WebDriverWait(browser, 15).until(
        EC.presence_of_element_located((By.CSS_SELECTOR, 'a:contains("mail")'))
    )
finally:
    browser.quit()

Immediately, the following error is printed on the console:

Traceback (most recent call last):
  File "/some/path/test_contains.py", line 13, in <module>
    EC.presence_of_element_located((By.CSS_SELECTOR, 'a:contains("mail")'))
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/support/wait.py", line 71, in until
    value = method(self._driver)
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/support/expected_conditions.py", line 63, in __call__
    return _find_element(driver, self.locator)
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/support/expected_conditions.py", line 311, in _find_element
    raise e
selenium.common.exceptions.InvalidElementStateException: Message: invalid element state: Failed to execute 'querySelector' on 'Document': 'a:contains("mail")' is not a valid selector.
  (Session info: chrome=52.0.2743.116)
  (Driver info: chromedriver=2.9.248304,platform=Linux 4.4.0-36-generic x86_64)

The snippet for Firefox is as follows:

from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

browser = webdriver.Firefox()

browser.get('https://www.google.com/')

try:
    WebDriverWait(browser, 15).until(
        EC.presence_of_element_located((By.CSS_SELECTOR, 'a:contains("mail")'))
    )
finally:
    browser.quit()

It ends with timeout:

Traceback (most recent call last):
  File "/some/path/test_contains.py", line 13, in <module>
    EC.presence_of_element_located((By.CSS_SELECTOR, 'a:contains("mail")'))
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/support/wait.py", line 80, in until
    raise TimeoutException(message, screen, stacktrace)
selenium.common.exceptions.TimeoutException: Message: 
Stacktrace:
    at FirefoxDriver.annotateInvalidSelectorError_ (file:///tmp/tmpb2DcYS/extensions/[email protected]/components/driver-component.js:10744)
    at FirefoxDriver.prototype.findElementInternal_ (file:///tmp/tmpb2DcYS/extensions/[email protected]/components/driver-component.js:10775)
    at FirefoxDriver.prototype.findElement (file:///tmp/tmpb2DcYS/extensions/[email protected]/components/driver-component.js:10779)
    at DelayedCommand.prototype.executeInternal_/h (file:///tmp/tmpb2DcYS/extensions/[email protected]/components/command-processor.js:12661)
    at DelayedCommand.prototype.executeInternal_ (file:///tmp/tmpb2DcYS/extensions/[email protected]/components/command-processor.js:12666)
    at DelayedCommand.prototype.execute/< (file:///tmp/tmpb2DcYS/extensions/[email protected]/components/command-processor.js:12608)

Answer 1

CSS: The CSS2 contains function is not in CSS3; however, Selenium supports the superset of CSS1, 2, and 3.

contains() is not part of the current CSS3 specification so it will not work on all browsers, only ones that implemented it before it was pulled.

have a look

Refer This For better understanding