third_party/blink/web_tests/fast/files/blob-reading-from-form-file.html

<form id="form">
	<input id="file" multiple type="file" name="file">
</form>

<script src="../../resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>
<script type="text/javascript">

promise_test((t) => {
  eventSender.beginDragWithFiles(
    ['resources/UTF8.txt', 'resources/UTF8-2.txt']);
  eventSender.mouseMoveTo(10, 10);
  eventSender.mouseUp();

  var form = document.getElementById('form');
  var formData = new FormData(form);
  var request = new Request('/', {
    method: 'POST',
    body: formData
  });
  return request.text().then(text => {
    assert_true(text.search('WebKitFormBoundary') > 0,
                'the boundary is contained');
    assert_true(text.search('Hello') > 0, 'UTF8.txt is contained');
    assert_true(text.search('Wonderful') > 0, 'UTF8-2.txt is contained');
  });
}, "Reading a text from form files.");


promise_test((t) => {
  eventSender.beginDragWithFiles(['resources/UTF8.txt']);
  eventSender.mouseMoveTo(10, 10);
  eventSender.mouseUp();

  var file = document.getElementById('file');
  var formData = new FormData();
  formData.append('file', file.files[0]);
  assert_equals(file.files[0].size, 5, 'file size');
  var request = new Request('/', {
    method: 'POST',
    body: formData
  });
  return request.text().then(text => {
    assert_true(text.search('WebKitFormBoundary') > 0,
                'the boundary is contained');
    assert_true(text.search('Hello') > 0, 'UTF8.txt is contained');
    assert_true(text.search('Wonderful') < 0, 'UTF8-2.txt is not contained');
  });
}, "Reading a text from a generated form data.");

</script>