chromium/third_party/blink/web_tests/external/wpt/html/editing/dnd/images/010.html

<!doctype html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/resources/testdriver.js"></script>
<script src="/resources/testdriver-vendor.js"></script>
<script src="/resources/testdriver-actions.js"></script>
<script src="../resources/test-helper.js"></script>
<head>
<title>Image drag and drop to iframe</title>
<style type="text/css">
p:first-child
  {padding-left:20px;}
iframe
  {width:160px;
  height:160px;
  border-style:none;}
</style>
</head>
<body>
<p><img src="../resources/circle.png" alt="PNG circle" ondragstart="event.dataTransfer.effectAllowed = 'copy'"/></p>
<p>Drag circle above to the box below. It should be copied to the box once you drop it there.</p>
<p><iframe src="helper-drop-image-here.xhtml">XHTML with image</iframe></p>
<script>
async function test() {
  await new Promise(loaded => window.addEventListener("load", loaded));
  const img = document.querySelector('img');
  const iframe = document.querySelector('iframe');
  const innerDoc = iframe.contentDocument || iframe.contentWindow.document;
  const div = innerDoc.querySelector('div');
  function onDropCallBack(event) {
    assert_equals(img.src, event.dataTransfer.getData('text/uri-list').replace(/\r\n$/,''));
    return true;
  }
  dragDropTest(img, div, onDropCallBack, 'Dragging an image to an iframe should copy it there', iframe)
};
test();
</script>
</body>
</html>