Fix test errors when PostgreSQL or MySQL are not available

tests/cases/Database/Base.php

@@ -100,10 +100,12 @@ abstract class Base extends \JKingWeb\Arsse\Test\AbstractTest {
     }
 
     public static function tearDownAfterClass() {
-        // wipe the database absolutely clean
+        if (static::$drv) {
-        static::dbRaze(static::$drv);
+            // wipe the database absolutely clean
-        // clean up
+            static::dbRaze(static::$drv);
-        static::$drv = null;
+            // clean up
+            static::$drv = null;
+        }
         static::$failureReason = "";
         static::clearData();
     }

tests/cases/DatabaseDrivers/MySQL.php

@@ -18,7 +18,7 @@ trait MySQL {
     protected static $stringOutput = true;
     
     public static function dbInterface() {
-        $d = new \mysqli(Arsse::$conf->dbMySQLHost, Arsse::$conf->dbMySQLUser, Arsse::$conf->dbMySQLPass, Arsse::$conf->dbMySQLDb, Arsse::$conf->dbMySQLPort);
+        $d = @new \mysqli(Arsse::$conf->dbMySQLHost, Arsse::$conf->dbMySQLUser, Arsse::$conf->dbMySQLPass, Arsse::$conf->dbMySQLDb, Arsse::$conf->dbMySQLPort);
         if ($d->connect_errno) {
             return;
         }