chromium/third_party/blink/web_tests/external/wpt/workers/Worker_ErrorEvent_type.htm

<!DOCTYPE html>
<title> AbstractWorker ErrorEvent.type </title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<div id=log></div>
<script>
// The worker events races with the window's load event; if the worker events
// arrive first, the harness will detect the error event and fail the test.
setup({ allow_uncaught_exception: true });

async_test(function(t) {
  var worker = new Worker('./support/ErrorEvent.js');
  worker.onerror = t.step_func_done(function(e) {
    assert_class_string(e, 'ErrorEvent');
    assert_equals(e.type, 'error');
  });
  worker.postMessage("Error Message");
});
</script>