navigation-api/navigate-event/intercept-multiple-times.html

<!doctype html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>
promise_test(async t => {
  let p1_resolved = false;
  let p2_resolved = false;
  let p3_resolved = false;
  navigation.onnavigate = t.step_func(e => {
    e.intercept({ handler: async () => {
      await Promise.resolve();
      assert_false(p2_resolved);
      assert_false(p3_resolved);
      p1_resolved = true;
    }});
    e.intercept({ handler: async () => {
      await new Promise(resolve => t.step_timeout(resolve, 1));
      assert_true(p1_resolved);
      assert_false(p3_resolved);
      p2_resolved = true;
    }});
    e.intercept({ handler: async () => {
      await new Promise(resolve => t.step_timeout(resolve, 1));
      assert_true(p1_resolved);
      assert_true(p2_resolved);
      p3_resolved = true;
    }});
  });

  let promise = navigation.navigate("#1").finished;
  assert_equals(location.hash, "#1");
  assert_false(p1_resolved);
  assert_false(p2_resolved);
  assert_false(p3_resolved);

  await promise;
  assert_true(p1_resolved);
  assert_true(p2_resolved);
  assert_true(p3_resolved);
}, "navigation.navigate() returns a finished promise that awaits all promises if event.intercept() is called multiple times");
</script>