Test async page changes with the intern

Lets say I have a button and a div element on a page.

<button /><div>old text</div>

By clicking on button, javascript asynchronously change the text of the div (i.e. after ajax call). How can i test it with intern?

This does not work:

function testButtonClick() {
      return command
                 .findByTagName('button')
                 .click()
                 .end()
                 .findByTagName('div')
                 .getVisibleText()
                 .then(function(text) { assert.strictEqual(text,'new text')}); //errror, text is 'old text'
}

If I add .sleep(5000) after .end(), then it works Ok (because my async request is usually done in 5 seconds). But I do not want to wait so long, because the async is usually finished much earlier.

But using sleep with lower time value, I risk that it will be tested before the request is finished.

Is there a better way?