Add AbstractTestCase to hold common test methods.

Author: Potherca

tests/unit/AbstractTestCase.php

@@ -0,0 +1,9 @@
+<?php declare(strict_types=1);
+
+namespace Pdsinterop\Solid\Auth;
+
+use PHPUnit\Framework\TestCase;
+
+abstract class AbstractTestCase extends TestCase
+{
+}