Handling self-refreshing pages from selenium

Question

I have been running into intermittent errors with some java selenium-rc tests which I think are related to a page which has an ajax poll and automatically refreshes when some condition is reached on the server. In this scenario, I have no way of asking selenium to wait for the page to load, and so I run into a bunch of random "Couldn't access document.body" errors.

So, is there some way I can cause selenium to gracefully handle this situation? If not, is there some way I could detect whether the user is selenium from the page's javascript, and disable the automatic refresh?

If it helps at all, the javascript code in the page looks something like...

var ajax = new Ajax(url, { 
    update: state,
    method: 'get',
    onComplete: function(message) {
        if (some_condition) {
            window.location.replace(unescape(window.location));
        }
    }
});

Answer 1

One solution might be to always use a waitForCondition using isElementPresent before attempting to interact with the application under test. You could put the following method in a superclass to keep your tests more readable. Alternatively you could create helper methods for common Selenium commands that perform this wait.

/** Waits for an element to be present */
public static void waitForElementToBePresent(String locator) {
    session().waitForCondition("var value = selenium.isElementPresent('" + locator.replace("'", "\\'") + "'); value == true", "60000");
}

You may also want to wait for the element to be visible, as waiting for it to just be present isn't always enough (imagine a textbox that is always present but hidden until a certain condition). You can combine this with the above method:

/** Waits for an element to be visible */
public static void waitForElementToBeVisible(String locator) {
    waitForElementToBePresent(locator);
    session().waitForCondition("var value = selenium.isVisible('" + locator.replace("'", "\\'") + "'); value == true", TIMEOUT);
}

Incidentally, the WebDriver (Selenium 2) team are working on having implicit waits, specifically to address AJAX issues where elements are not present immediately.