public function testForcedAuthn()
{
$state = array('ForceAuthn' => true);
/** @var \SAML2\AuthnRequest $ar */
$ar = $this->createAuthnRequest($state);
$this->assertEquals($state['ForceAuthn'], $ar->getForceAuthn());
/** @var $xml \DOMElement */
$xml = $ar->toSignedXML();
$q = \SAML2\Utils::xpQuery($xml, '/samlp:AuthnRequest/@ForceAuthn');
$this->assertEquals($state['ForceAuthn'] ? 'true' : 'false', $q[0]->value);
}