chromium/content/test/data/accessibility/event/add-alert-with-empty-text.html

<!--
@WIN-DENY:EVENT_OBJECT_LOCATIONCHANGE*
@WIN-DENY:EVENT_OBJECT_REORDER*
@UIA-WIN-DENY:StructureChanged/*
-->
<!DOCTYPE html>
<html>
<body>
<div id="foo" role="alert"></div>
<div id="bar" role="alert"></div>
<div role="alert">
  <p id="baz"></p>
</div>
<div id="hidden_alert_non_empty_text" style="display: none;" role="alert">
  Hello world!!
</div>
<div id="hidden_alert_empty_text" style="display: none;" role="alert"></div>
<script>
  function go() {
    // Should fire an alert event.
    document.getElementById("foo").innerHTML = "First alert";
    // Shouldn't fire an alert event.
    document.getElementById("bar").innerHTML = "";
    // Shouldn't fire an alert event.
    document.getElementById("baz").innerHTML = "     ";
    // Should fire an alert event.
    document.getElementById("hidden_alert_non_empty_text").style.display = "block";
    // Shouldn't fire an alert event.
    document.getElementById("hidden_alert_empty_text").style.display = "block";
  }
</script>
</body>
</html>