on() {
        var container = fixture('manual-validate-numbers');
        var input = Polymer.dom(container).querySelector('#i');
        var inputContent = Polymer.dom(container.root).querySelector('.input-content');
        var line = Polymer.dom(container.root).querySelector('.underline');

        input.bindValue = 'foobar';
        input.validate();

        assert.isTrue(container.invalid, 'invalid is true');
        assert.isTrue(inputContent.classList.contains('is-invalid'), 'label has invalid styl