add Db test

Author: ylebre

tests/phpunit/DbTest.php

@@ -0,0 +1,13 @@
+<?php
+    namespace Pdsinterop\PhpSolid;
+
+    use Pdsinterop\PhpSolid\Db;
+
+    const DBPATH = ":memory:";
+    class DbTest extends \PHPUnit\Framework\TestCase
+    {
+        public function testConnect() {
+            Db::connect();
+            $this->assertInstanceOf("PDO", Db::$pdo);
+        }
+    }