public function testExtraViewChild()
 {
     $view = $this->factoryBuilder->addTypeExtension(new ExtraViewChildrenExtension(array('extra1', 'extra2')))->getFormFactory()->createBuilder()->add('foo', 'form', array('position' => 'last'))->add('bar', 'form', array('position' => 'first'))->getForm()->createView();
     $this->assertPositions($view, array('bar', 'foo', 'extra1', 'extra2'));
 }