Mixing implicit and explicit waits

Question

The docs say:

An implicit wait is to tell WebDriver to poll the DOM for a certain amount of time when trying to find an element or elements if they are not immediately available.

Sub-question:

In the case of find_elements_by_ (plural), how many elements does implicit_wait wait for to exist before continuing with your script? Or does implicit_wait only work with find_element_by_ (singular)? If so what do the docs mean by "or elements"?

From an SO answer I read that it's best not to use both implicit and explicit waits in the same script, which I took notice of as I'd like the tests to be as robust as possible.

Since I know there are times I'll definitely need WebDriverWait, does this mean I need to get rid of implicit_wait in my unittest setUp method and instead employ WebDriverWait every single time I use any find_element_by_ method?

(I'd rather not have to do this; although I suppose I could put each of the find_element_by_ methods in my own custom functions -each wrapped in their own WebDriverWait -it feels like I shouldn't have to).

So my main question is:

Can I instead keep my implicit_wait in my test setUp method, and then only use WebDriverWait when it comes to find_elements_by_ and other places where I know I need it?

I wouldn't mix the two. I would use WebDriverWait each time. Selenium has no idea about when you need to wait for an element to be in a specific state before it's usable. That's why the option is there. Besides, an implicit is going to wait until the element is found. An element being found is not equal to an element being usable. — Arran
+1 I didn't know there was a distinction. I'm starting to wonder why implicitly_wait is in the API at all! How would you check for an element being usable? I see expected_conditions.element_to_be_clickable but not sure what else I'd use. — KnewB
possible duplicate of selenium webdriver - explicit wait vs implicit wait — lesmana

Louis Louis · Accepted Answer · 2013-11-28T14:49:09

Since I know there are times I'll definitely need WebDriverWait, does this mean I need to get rid of implicit_wait in my unittest setUp method and instead employ WebDriverWait every single time I use any find_element_by_ method?

Yes. As you've seen in the question you link to, if you use both types of waits, you're going to run into undesirable behavior. It's not just theoretical. I've experienced that behavior first hand, tried to debug it, found the question you linked to and then removed all implicit waits from my test suites.

I developed a library to help with setting up the explicit waits (and do a bunch of other things). Assuming you already have a driver object that has the selenium web driver:

from selenium.webdriver.common.by import By
import selenic.util

util = selenic.util.Util(driver)

# This goes through util and uses the explicit wait set by util.
foo = util.find_element((By.CSS_SELECTOR, "..."))

# For special cases that take longer to give results.
with util.local_timeout(10):
    # The timeout is set to 10 for calls in this with block.
    bar = util.find_element(...)
# The timeout is restored to what it was just before the with.

There are some times when you don't need to use waits at all because logically if element A is present then B is also present, so you don't have to wait for it. For instance. if you want the parent of an element you've already obtained from Selenium, you can do parent = foo.find_element_by_xpath("..").

As for the behavior of find_elements, it returns as soon as it determines that there is a result to return. This could mean getting only one element if later elements do show up after find_elements has found something to return.

Mixing implicit and explicit waits

1 Answers