ParagonIE\GPGMailer\GPGMailer::setPrivateKey PHP Method

    public function setPrivateKey(string $serverKey) : self
    {
        $this->serverKeyFingerprint = $this->import($serverKey);
        return $this;
    }

 /**
  * @covers GPGMailer::decrypt()
  * @covers GPGMailer::encrypt()
  */
 public function testEncryptedMessage()
 {
     // First, create a Zend\Mail message as usual:
     $plaintext = 'Cleartext for now. Do not worry; this gets encrypted. Don\' actually send this, however.';
     $plaintext .= \random_bytes(32);
     $message = new Message();
     $message->addTo('*****@*****.**', 'GPGMailer Test Email');
     $message->setBody($plaintext);
     // Instantiate GPGMailer:
     $gpgMailer = new GPGMailer(new File(), ['homedir' => '~']);
     $publicKey = file_get_contents(__DIR__ . '/public.key');
     $fingerprint = $gpgMailer->import($publicKey);
     $encrypted = $gpgMailer->encrypt($message, $fingerprint);
     $body = $encrypted->getBodyText();
     $this->assertTrue(\strpos($body, '-----BEGIN PGP MESSAGE-----') !== false);
     $privateKey = file_get_contents(__DIR__ . '/private.key');
     $gpgMailer->setPrivateKey($privateKey);
     $decrypted = $gpgMailer->decrypt($encrypted);
     $this->assertSame($plaintext, $decrypted->getBodyText());
 }