custom-elements/reactions/with-exceptions.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>Custom Elements: CEReactions interaction with exceptions</title>
<link rel="author" title="Domenic Denicola" href="mailto:d@domenic.me">
<meta name="help" content="https://html.spec.whatwg.org/multipage/#cereactions">
<meta name="help" content="https://github.com/whatwg/html/pull/3235">

<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="../resources/custom-elements-helpers.js"></script>

<div id="log"></div>

<script>
"use strict";
// Basically from https://github.com/whatwg/html/issues/3217#issuecomment-343633273
test_with_window((contentWindow, contentDocument) => {
  let reactionRan = false;
  contentWindow.customElements.define("custom-element", class extends contentWindow.HTMLElement {
    disconnectedCallback() {
      reactionRan = true;
    }
  });
  const text = contentDocument.createTextNode("");
  contentDocument.documentElement.appendChild(text);
  const element = contentDocument.createElement("custom-element");
  contentDocument.documentElement.appendChild(element);
  assert_throws_dom(
    "HierarchyRequestError",
    contentWindow.DOMException,
    () => text.before("", contentDocument.documentElement)
  );
  assert_true(reactionRan);
}, "Reaction must run even after the exception is thrown");
</script>