<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS Transitions Test: transition-property - background-position</title>
<link rel="author" title="Zhuoyu Qian" href="mailto:zhuoyu.qian@samsung.com">
<link rel="help" href="https://drafts.csswg.org/web-animations-1/#animation-type">
<link rel="help" href="https://drafts.csswg.org/css-backgrounds-3/#background-position">
<meta name="assert" content="Test checks that the 'background-position' property with edge offset is animatable.">
<script src="/resources/testharness.js" type="text/javascript"></script>
<script src="/resources/testharnessreport.js" type="text/javascript"></script>
<style>
  #test {
    border: 1px solid;
    background-image: url("support/cat.png");
    background-repeat: no-repeat;
    height: 200px;
    transition-duration: 100s;
    transition-property: background-position;
    transition-timing-function: step-end;
  }
</style>
<body>
  <div id="test"></div>
</body>
<script>
var startValue = "left 10px top 10px";
var endValue = "right 10px bottom 10px";
var div = document.getElementById("test");

// getComputedStyle helper
function gCS(aProperty) {
  return document.defaultView
         .getComputedStyle(div, "")
         .getPropertyValue(aProperty);
}

(function() {
  div.style.backgroundPosition = startValue;

  // flush styles
  gCS("background-position");

  // set property to endValue
  div.setAttribute("style", "background-position: " + endValue);

  test(function() {
    assert_true(gCS("background-position") != endValue);
  }, "background-position not equals to end value");
})();
</script>