How to fix this python-selenium try-except block?

Question

I have a python class to handle some basic selenium stuff. One of the methods is a wrapper to check if some element is present on the page:

from selenium.common.exceptions import TimeoutException, NoSuchElementException

...

def check_element(self, by, element):
    try:
        self.driver.find_element(by, element)  
        return True
    except TimeoutException, NoSuchElementException:
        return False

I call this method with something like this:

self._base.check_element((By.XPATH, '//*[@id="kernel_indicator_icon"]))

But when running the code I get an unexpected error:

  ...
  File "/Users/adietz/Projects/Jenkins/selenium-tests/selenium_tests/tools/basicsuite.py", line 277, in check_element
    self.driver.find_element(by, element)
  File "/Users/adietz/Projects/Jenkins/venv_selenium/lib/python2.7/site-packages/selenium/webdriver/remote/webdriver.py", line 858, in find_element
    'value': value})['value']
  File "/Users/adietz/Projects/Jenkins/venv_selenium/lib/python2.7/site-packages/selenium/webdriver/remote/webdriver.py", line 311, in execute
    self.error_handler.check_response(response)
  File "/Users/adietz/Projects/Jenkins/venv_selenium/lib/python2.7/site-packages/selenium/webdriver/remote/errorhandler.py", line 237, in check_response
    raise exception_class(message, screen, stacktrace)
NoSuchElementException: Message: Unable to locate element: //*[@id="kernel_indicator_icon" and @title="Kernel Idle"]

Why hasn't this exception been caught by the try-except block above?

Answer 1

Straigh from the documentation

def check_element(self, by, element):
    try:
        self.driver.find_element(by, element)  
        return True
    except (TimeoutException, NoSuchElementException) as e:
        return False