chromium/third_party/blink/web_tests/external/wpt/html/semantics/embedded-content/the-img-element/empty-src-no-current-request.html

<!doctype html>
<meta charset="utf-8">
<title>src = "" doesn't trigger a sync load if there's no existing current request</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1905646">
<script>
  promise_test(async function(t) {
    let img = new Image();
    img.src = "";
    img.loading = "lazy";
    img.onload = t.unreached_func("should not trigger a load event");
    img.onerror = t.unreached_func("should not trigger an error event");
    // Shouldn't fire any event since it's in the lazy state.
    await new Promise(r => t.step_timeout(r, 0));
    await new Promise(r => t.step_timeout(r, 0));

    // We're about to append it to the document, which should trigger the (lazy) load (and in this case error event).
    let error = new Promise(r => {
      img.onerror = r;
    });
    document.documentElement.appendChild(img);
    await error;
  }, "Without srcset");

  promise_test(async function(t) {
    let img = new Image();
    img.src = "";
    img.srcset = "/images/green.png";
    img.loading = "lazy";
    img.onload = t.unreached_func("should not trigger a load event");
    img.onerror = t.unreached_func("should not trigger an error event");
    // Shouldn't fire any event since it's in the lazy state.
    await new Promise(r => t.step_timeout(r, 0));
    await new Promise(r => t.step_timeout(r, 0));

    // We're about to append it to the document, which should trigger the (lazy) load.
    let load = new Promise(r => {
      img.onload = r;
    });

    document.documentElement.appendChild(img);
    await load;
  }, "With srcset");
</script>