textarea-insertfrompaste-type-inputevent-data-withnewline-atstart.html

<!DOCTYPE html>
<html>
<body>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<textarea id="text" cols=60>Copying and pasting second line including interchange newline
at the start should set the event.data with the selected part for inputType
insertFromPaste</textarea>
<script>
  const text = document.getElementById("text");
  let eventData;
  text.addEventListener('input', (evt) => {
    if(evt.inputType == 'insertFromPaste')
      eventData = evt.data;
  });
  test(function () {
    text.focus();
    // Selecting second line inluding interchange newline at start
    text.setSelectionRange(61, 137);
    const selectedData = getSelection().toString();
    // Copy and paste should fire input event with inputType insertFromPaste.
    document.execCommand("copy");
    document.execCommand("paste");
    // Event data should now be set with the second line of the text
    assert_equals(selectedData, "\nat the start should set the event.data with the selected part for inputType");
    assert_equals(eventData, selectedData);
  }, 'Input event data for inputType insertFromPaste should be set');
</script>
</body>
</html>

chromium/third_party/blink/web_tests/external/wpt/input-events/textarea-insertfrompaste-type-inputevent-data-withnewline-atstart.html