public function testContainerOptions()
{
$containerClass = "dropup";
ButtonDropdown::$counter = 0;
$out = ButtonDropdown::widget(['containerOptions' => ['class' => $containerClass], 'label' => 'Action', 'dropdown' => ['items' => [['label' => 'DropdownA', 'url' => '/'], ['label' => 'DropdownB', 'url' => '#']]]]);
$this->assertContains("{$containerClass} btn-group", $out);
}
