Selenium tests against AJAX applications

In our example, we will click on a link and then assert that some text is visible on the screen:

Have a look at the page that you are working against. Can you see the text that the test is expecting? You should see it, so why has this test failed? The test has failed because when the test reached that point, the element containing the text was not loaded into the DOM. This is because it was being requested and rendered from the web server into the browser.

To remedy this issue, we will need to add a new command to our test so that our tests pass in the future:

Selenium does not implicitly wait for the item that it needs to interact with, so it is seen as good practice to wait for the item you need to work with and then interact with it. The waitFor commands will timeout after 30 seconds by default, but if you need it to wait longer, you can specify the tests by using the setTimeout command. This will set the timeout value that the tests will use in future commands.

If need be, you can change the default wait if you go to Options | Options and then on the General tab, and under Default timeout value of recorded command in milliseconds (30s = 30,000ms) change it to what you want. Remember, 1,000 milliseconds = 1 second.

As more and more applications try to act like desktop applications, we need to be able to handle synchronization steps between our test and our application. In this section, we will see how to handle AJAX and what to synchronize:

In the previous examples, we waited for an element to appear on the page; there are a number of different commands that we can use to wait. Also, remember that we can take advantage of waiting for something not to be on the page, for example, waitForElementNotPresent. This can be just as effective as waiting for it to be there.

The following commands make up the waitFor set of commands, but this is not an exhaustive list:

A number of these commands are run implicitly when other commands are being run. An example of this is the clickAndWait command. This will fire off a click command and then fire off a waitForPageToLoad command. Another example is the open command, which only completes when the page has fully loaded.

If you are feeling confident, then it's a good time to try different waitFor command techniques.