/**
* @covers ::addCleanValueKey
*/
public function testAddCleanValueKey()
{
$form_state = new FormState();
$form_state->setValue('value_to_clean', 'rainbow_sprinkles');
$form_state->addCleanValueKey('value_to_clean');
$this->assertSame($form_state->getCleanValueKeys(), ['form_id', 'form_token', 'form_build_id', 'op', 'value_to_clean']);
return $form_state;
}