navigation-api/ordering-and-transition/transition-realms-and-identity.html

<!doctype html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>

<iframe id="i" src="/common/blank.html"></iframe>

<script>
promise_test(async () => {
  await new Promise(resolve => window.onload = resolve);

  i.contentWindow.navigation.addEventListener("navigate", e => {
    e.intercept();
  });

  const returnValueFinished1 = i.contentWindow.navigation.navigate("?1").finished;
  const transition1 = i.contentWindow.navigation.transition;
  const transitionFinished1 = transition1.finished;

  assert_true(returnValueFinished1 instanceof i.contentWindow.Promise);
  assert_true(transition1 instanceof i.contentWindow.NavigationTransition);
  assert_true(transitionFinished1 instanceof i.contentWindow.Promise);

  assert_not_equals(returnValueFinished1, transitionFinished1);

  // Ensure the getters aren't generating new objects each time.
  assert_equals(i.contentWindow.navigation.transition, transition1);
  assert_equals(i.contentWindow.navigation.transition.finished, transitionFinished1);

  assert_equals(await transitionFinished1, undefined);

  // Ensure stuff does change after another navigation.
  const committed2 = i.contentWindow.navigation.navigate("?2").committed;
  const transition2 = i.contentWindow.navigation.transition;
  const transitionFinished2 = transition2.finished;

  assert_not_equals(transition2, transition1);
  assert_not_equals(transitionFinished2, transitionFinished1);

  await committed2;
}, "Realm and identity of the navigation.transition object and its finished promise");
</script>