added phpunit and composer stuff

tests/unit/TestUser.php

@@ -0,0 +1,16 @@
+<?php
+declare(strict_types=1);
+
+use PHPUnit\Framework\TestCase;
+use model\forum\User;
+
+final class TestUser extends TestCase
+{
+    public function testCanBeCreatedFromValidEmailAddress(): void
+    {
+        $this->assertInstanceOf(
+            User::class,
+            new User(1, 'andreas', 'andreas@example.com', 'password', '10-04-2019 12:00:00', '10-04-2019 12:00:00', '94.212.253.51', -1, 1)
+        );
+    }
+}