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Tuesday, March 16, 2010

Selenium RC [Java] waitForCondition example

I've seen a few people post questions about using the Selenium waitForCondition method.

If you read the documentation for the waitForCondition method (in either Selenium or DefaultSelenium) you will see a mention of selenium.browserbot.getCurrentWindow(). This is key to the wait for condition.

When you start a test case there are two windows which open up. The first window has the Selenium Command History and ability to display the log. I call this the Selenium window. The next window which opens is the window for the application under test or AUT window.

The waitForCondition method has two parameters. The second parameter is the easiest to understand. We don't want the test to wait for ever. If we don't get a response by a certain time we can assume the test failed. The second parameter is the timeout period in milliseconds. So if the condition should occur within 20 seconds, the second parameter is "20000".

The second parameter is the key to the waiting. It is the condition we are waiting for. There are two windows open, Selenium and AUT. The first parameter to waitForCondition is a javascript expression. It will normally be tested on the Selenium window. If you want to evaluate some javascript in the AUT window you need to use: selenium.browserbot.getCurrentWindow(). For example, Let's say this is the AUT window:

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
<script type="text/javascript">
// this variable is the key. When it is false the loading is done
var loading=true;

function loadingDone() {

// hidden the GIF
document.getElementById("loading").style.visibility="hidden"; // set the flag to indicate we are done loading
// this sets a timer for ten seconds to simulate something
// loading for ten seconds. After ten seconds this will call
// the loadingDone() function.
var seconds=10;
var t=setTimeout("loadingDone()", seconds * 1000);

<!-- the moment the page loads this will create -->
<!-- a spinning GIF to signal something loading -->
<img id="loading" src="" style="visibility:visible"/>

What this page does is simulate something loading. After 10 seconds it will hide the spinning GIF and set the loading variable to false. So the condition we are waiting for is when loading == false.

This means from waitForCondition we want to look at the variable "selenium.browserbot.getCurrentWindow().loading == false". In other words, the full statement is going to be:

selenium.waitForCondition("selenium.browserbot.getCurrentWindow().loading == false", "20000");

It is important to note that the selenium in selenium.waitForCondition is a Java object in your test code and the selenium in selenium.browserbot is a javascript object running in the web browser.

Let's say we take this HTML and save it to the file /Users/darrell/workspace/LearningSelenium/waitForCondition.html then we can create the following Selenium RC test case:

package com.example.tests;

import org.openqa.selenium.server.RemoteControlConfiguration;
import org.openqa.selenium.server.SeleniumServer;
import com.thoughtworks.selenium.DefaultSelenium;
import com.thoughtworks.selenium.SeleneseTestCase;

public class TestingSelenium extends SeleneseTestCase {

 SeleniumServer ss;
 RemoteControlConfiguration rcc = new RemoteControlConfiguration();

 public void setUp() throws Exception {
  int ssPort = 4444;
  ss = new SeleniumServer(rcc);
  selenium = new DefaultSelenium("localhost", ssPort, "*safari", "file://");

 public void testStub() throws Exception {
  long start, stop;"/Users/darrell/workspace/LearningSelenium/waitForCondition.html");
  start = System.currentTimeMillis();
  selenium.waitForCondition("selenium.browserbot.getCurrentWindow().loading == false", "300000");
  stop = System.currentTimeMillis();
  System.err.println("Elapsed time: " + ((stop - start) / 1000.0) + " seconds");

 public void tearDown() throws Exception {

and that is one example of waitForCondition. You will have to know what condition to wait for in your application. If you are using AJAX you might find there is an AJAX object on your application. In it will be a activeRequestCount. When the AJAX.activeRequestCount goes to zero, all the AJAX calls are done. So you can wait for an AJAX call to complete with:

selenium.waitForCondition("selenium.browserbot.getCurrentWindow().AJAX.activeRequestCount == 0", "30000");

1 comment:

Anonymous said...

very usefull