/**
* @covers ::prepareCallback
*/
public function testPrepareCallbackArray()
{
$form_state = new FormState();
$form_state->setFormObject(new PrepareCallbackTestForm());
$callback = [$form_state->getFormObject(), 'buildForm'];
$processed_callback = $form_state->prepareCallback($callback);
$this->assertEquals($callback, $processed_callback);
}