Add a database trait (see #3)

Description
-----------

Should be released as v1.6

Commits
-------

c8130ac Added DatabaseTrait
8ec4825 Change ext-pdo to be optional
b27c362 Throw an exception if the SQL file does not exist

composer.json

@@ -13,6 +13,7 @@
         "php": "^7.1"
     },
     "require-dev": {
+        "ext-pdo": "*",
         "contao/core-bundle": "^4.5",
         "friendsofphp/php-cs-fixer": "^2.12",
         "php-http/guzzle6-adapter": "^1.1",

src/ContaoDatabaseTrait.php

@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of Contao.
+ *
+ * (c) Leo Feyer
+ *
+ * @license LGPL-3.0-or-later
+ */
+
+namespace Contao\TestCase;
+
+trait ContaoDatabaseTrait
+{
+    private static $pdo;
+
+    protected static function loadFileIntoDatabase(string $sqlFile): void
+    {
+        if (!file_exists($sqlFile)) {
+            throw new \InvalidArgumentException(sprintf('File "%s" does not exist', $sqlFile));
+        }
+
+        $pdo = static::getConnection();
+        $pdo->exec(file_get_contents($sqlFile));
+    }
+
+    protected static function getConnection(): \PDO
+    {
+        if (null === self::$pdo) {
+            self::$pdo = new \PDO(
+                sprintf('mysql:host=%s;port=%s;dbname=%s;', getenv('DB_HOST'), getenv('DB_PORT'), getenv('DB_NAME')),
+                getenv('DB_USER'),
+                getenv('DB_PASS'),
+                [\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION]
+            );
+        }
+
+        return self::$pdo;
+    }
+}