<!DOCTYPE html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/test-helpers.sub.js"></script>
<body>
<script>
promise_test(function (t) {
    var currentState = 'test-is-starting';
    var scope = 'resources/state/';

    return service_worker_unregister_and_register(
        t, 'resources/empty-worker.js', scope)
      .then(function(registration) {
          t.add_cleanup(function() {
              return service_worker_unregister(t, scope);
            });

          var sw = registration.installing;

          assert_equals(sw.state, 'installing',
                        'the service worker should be in "installing" state.');
          checkStateTransition(sw.state);
          return onStateChange(sw);
        });

    function checkStateTransition(newState) {
        switch (currentState) {
        case 'test-is-starting':
            break; // anything goes
        case 'installing':
            assert_in_array(newState, ['installed', 'redundant']);
            break;
        case 'installed':
            assert_in_array(newState, ['activating', 'redundant']);
            break;
        case 'activating':
            assert_in_array(newState, ['activated', 'redundant']);
            break;
        case 'activated':
            assert_equals(newState, 'redundant');
            break;
        case 'redundant':
            assert_unreached('a ServiceWorker should not transition out of ' +
                             'the "redundant" state');
            break;
        default:
            assert_unreached('should not transition into unknown state "' +
                             newState + '"');
            break;
        }
        currentState = newState;
    }

    function onStateChange(expectedTarget) {
      return new Promise(function(resolve) {
            expectedTarget.addEventListener('statechange', resolve);
          }).then(function(event) {
            assert_true(event.target instanceof ServiceWorker,
                        'the target of the statechange event should be a ' +
                        'ServiceWorker.');
            assert_equals(event.target, expectedTarget,
                          'the target of the statechange event should be ' +
                          'the installing ServiceWorker');
            assert_equals(event.type, 'statechange',
                          'the type of the event should be "statechange".');

            checkStateTransition(event.target.state);

            if (event.target.state != 'activated')
                return onStateChange(expectedTarget);
          });
    }
}, 'Service Worker state property and "statechange" event');
</script>