public function testAllowUnset()
{
$form = new FormBlueprint();
$form->add('unset_allowed', 'input', array('allow_unset' => true, 'unset_value' => 'unset_value'));
$handler = new FormHandler($form);
$handler->handleRequest();
$this->assertTrue($handler->isSubmitted());
$processed_field = $handler->getProcessedField('unset_allowed');
$this->assertEquals('unset_value', $processed_field['value']);
}