mozilla-release/testing/web-platform/tests/resource-timing/object-not-found-adds-entry.html

<!doctype html>
<html>
<head>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
</head>
<body>
<script>
const test_object_entry = (url, type, test_name) => {
  promise_test(t => {
    return new Promise((resolve, reject) => {
      performance.clearResourceTimings();
      const el = document.createElement("object");
      const po = new PerformanceObserver(t.step_func(e => {
        const entries = e.getEntriesByType("resource");
        assert_greater_than(entries.length, 0, "Got a performance entry");

        assert_true(entries[0].name.includes(url), "Performance resource timing entry has the right name");
        po.disconnect();
        resolve();
      }));
      po.observe({type: "resource"});
      el.data = url;
      if (type) {
        el.type = type;
      }
      el.style = "width: 0px; height: 0px;";
      document.body.appendChild(el);

      el.onload = el.onerror = t.step_timeout(() => {
        assert_unreached("No performance entry was observed");
        reject();
      }, 500);
    });
  }, test_name);

};

test_object_entry("resources/status-code.py?status=404&type=none", null, "Test that an navigation object with a 404 response displays an entry");
test_object_entry("resources/status-code.py?status=200&type=none", null, "Test that an navigation object with a 200 response displays an entry");
test_object_entry("resources/status-code.py?status=404&type=img", "image/png", "Test that an image object with a 404 response displays an entry");

</script>