Fix rcube::decrypt() (#9264)

* do not skip test_encrypt_and_decrypt test
* Fix rcube::decrypt()

program/lib/Roundcube/rcube.php

@@ -958,7 +958,7 @@ class rcube
         $iv_size = openssl_cipher_iv_length($method);
         $tag     = null;
 
-        if (preg_match('/^##(.{16})##/', $cipher, $matches)) {
+        if (preg_match('/^##(.{16})##/s', $cipher, $matches)) {
             $tag    = $matches[1];
             $cipher = substr($cipher, strlen($matches[0]));
         }

tests/Framework/Rcube.php

@@ -46,21 +46,18 @@ class Framework_Rcube extends PHPUnit\Framework\TestCase
     function test_encrypt_and_decrypt()
     {
         $rcube = rcube::get_instance();
-        $result = $rcube->decrypt($rcube->encrypt('test'));
 
+        $result = $rcube->decrypt($rcube->encrypt('test'));
         $this->assertSame('test', $result);
 
-        // The following tests fail quite often, therefore we disable them
-        $this->markTestSkipped();
-
         // Test AEAD cipher method
+        $defaultCipherMethod = $rcube->config->get('cipher_method');
         $rcube->config->set('cipher_method', 'aes-256-gcm');
-
-        $result = $rcube->decrypt($rcube->encrypt('test'));
-
-        $this->assertSame('test', $result);
-
-        // Back to the default
-        $rcube->config->set('cipher_method', 'DES-EDE3-CBC');
+        try {
+            $result = $rcube->decrypt($rcube->encrypt('test'));
+            $this->assertSame('test', $result);
+        } finally {
+            $rcube->config->set('cipher_method', $defaultCipherMethod);
+        }
     }
 }