<!doctype html>
<title>Queue a task to fire popstate event</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<div id="log"></div>
<script>
t = async_test();
window.onload = t.step_func(function () {
  var states = [];

  var timer = null;

  history.pushState("a", "State a", "/a");
  history.pushState("b", "State b", "/b");

  history.back();
  window.onpopstate = t.step_func(function (e) {
    states.push(e.state);

    if (states.length === 2) {
      check_result();
    } else if (timer === null) {
      timer = setTimeout(function() {check_result()}, 500);
    }
  })

  check_result = t.step_func(function() {
    clearTimeout(timer);
    try {
      assert_array_equals(states, ["a", null]);
      t.done();
    } finally {
      location.hash = "";
    }
  });

  setTimeout(function() {history.back()}, 0);

});
</script>