Minishlink\WebPush\Utils::safeStrlen PHP Method

    public static function safeStrlen($string)
    {
        return mb_strlen($string, '8bit');
    }

 /**
  * @dataProvider vapidProvider
  *
  * @param $audience
  * @param $vapid
  * @param $expiration
  * @param $expectedAuthorization
  * @param $expectedCryptoKey
  */
 public function testGetVapidHeaders($audience, $vapid, $expiration, $expectedAuthorization, $expectedCryptoKey)
 {
     $vapid = VAPID::validate($vapid);
     $headers = VAPID::getVapidHeaders($audience, $vapid['subject'], $vapid['publicKey'], $vapid['privateKey'], $expiration);
     $this->assertArrayHasKey('Authorization', $headers);
     $this->assertEquals(Utils::safeStrlen($expectedAuthorization), Utils::safeStrlen($headers['Authorization']));
     $this->assertEquals($this->explodeAuthorization($expectedAuthorization), $this->explodeAuthorization($headers['Authorization']));
     $this->assertArrayHasKey('Crypto-Key', $headers);
     $this->assertEquals($expectedCryptoKey, $headers['Crypto-Key']);
 }