<!doctype html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<iframe id="i" src="/common/blank.html"></iframe>
<body>
<script>
promise_test(async t => {
  // Wait for after the load event so that the navigation doesn't get converted
  // into a replace navigation.
  await new Promise(resolve => window.onload = () => t.step_timeout(resolve, 0));

  await i.contentWindow.navigation.navigate("#1").finished;

  i.contentWindow.navigation.onnavigate = t.step_func(e => {
    assert_false(e.cancelable);
    // intercept() with a precommitHandler is forbidden because e.cancelable is false.
    let iframe_constructor = i.contentWindow.DOMException;
    assert_throws_dom("InvalidStateError", iframe_constructor,
                      () => e.intercept({ precommitHandler: async () => {} }));
  });
  await i.contentWindow.navigation.back().finished;
}, "precommitHandler for an uncancelable traverse navigation");
</script>
</body>