t.isTrue(element.messageElement.hidden);
  });

  test('should become visible when "missing" attribute is set', function() {
    const element = document.createElement('login-warning');
    Polymer.dom(element).setAttribute('missing', 'foo');
    Polymer.dom(document.body).appendChild(element);
    assert.isFalse(element.messageElement.hidden);
  });
});
</script>
