id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
30973	Selenium wait_page_loaded waits for wrong page (race condition)	Johannes Maron	Johannes Maron	"Right now `django.contrib.admin.tests.AdminSeleniumTestCase.wait_page_loaded` waits for the `body` HTML-tag to be present. It is meant to be executed after a page reload is triggered, like a form submit.

However, if the test suite is a little faster than our browser (race condition), we are looking get confirmation for the body tag of the old page, not the new one.

The safe (and correct) way to wait in selenium for a page to re reloaded is to wait until the old one is gone and the new one is ready. Preferably with a context manager like so:

{{{
@contextmanager
def wait_page_loaded(self, timeout=10):
    """"""
    Block until page has started to load.
    """"""
    from selenium.common.exceptions import TimeoutException
    from selenium.webdriver.support import expected_conditions as ec

    try:
        old_page = self.selenium.find_element_by_tag_name('html')
        yield
        # Wait for the next page to be loaded
        self.wait_until(ec.staleness_of(old_page), timeout=timeout)
        self.wait_until(
            lambda driver:
                driver.execute_script('return document.readyState;') == 'complete',
            timeout=timeout

        )
    except TimeoutException:
        # IE7 occasionally returns an error ""Internet Explorer cannot
        # display the webpage"" and doesn't load the next page. We just
        # ignore it.
        pass
}}}

In some cases we might also want to wait for a site to be ready after a regular `selenium.get`.
In that case with should have a separate method, like so:

{{{
    def wait_page_ready(self, timeout=10):
        """"""
        Block until page has started to load.
        """"""
        self.wait_until(
            lambda driver: driver.execute_script('return document.readyState;') == 'complete',
            timeout
        )
}}}

This bug currently affects a lot of tests and fails preferably when you run FireFox but I've seen it on Chrome too."	Bug	closed	Testing framework	dev	Normal	fixed	selenium		Ready for checkin	1	0	0	0	0	0