selenium.wait_for_condition equivalent in Python bindings for WebDriver

I'm moving some tests from Selenium to the WebDriver. My problem is that I can't find an equivalent for selenium.wait_for_condition. Do the Python bindings have this at开发者_如何学Python the moment, or is it still planned?

Currently it isn't possible to use wait_for_condition with WebDriver. The python selenium code does provide the DrivenSelenium class for accessing the old selenium methods, but it can't do wait_for_condition. The selenium wiki has some info on that.

Your best bet is to use the WebDriverWait class. This is a helper class that periodically executes a function waiting for it to return True. My general usage is

driver = webdriver.Firefox()
driver.get('http://example.com')
add = driver.find_element_by_id("ajax_button")
add.click()
source = driver.page_source

def compare_source(driver):
    try:
        return source != driver.page_source
    except WebDriverException:
        pass

WebDriverWait(driver, 5).until(compare_source)
# and now do some assertions

This solution is by no means ideal.. The try/except is necessary for situations where the page request/response cycle is delayed waiting for some ajax activity to complete. If compare_source get's called in the midst of the request/response cycle it'll throw a WebDriverException.

The test coverage for WebDriverWait is also helpful to look at.

Here's my version of Greg Sadetsky's answer, put into a function:

def click_n_wait(driver, button, timeout=5):
    source = driver.page_source
    button.click()
    def compare_source(driver):
        try:
            return source != driver.page_source
        except WebDriverException:
            pass
    WebDriverWait(driver, timeout).until(compare_source)

It clicks the button, waits for the DOM to change and then returns.

The Java binding include a Wait class. This class repeatedly checks for a condition (with sleeps between) until a timeout is reached. If you can detect the completion of your Javascript using the normal API, you can take the same approach.