Added some tests to constraint validators

tests/Validator/DummyUniqueValidatableObject.php

@@ -0,0 +1,41 @@
+<?php
+/*
+ * This file is part of Part-DB (https://github.com/Part-DB/Part-DB-symfony).
+ *
+ *  Copyright (C) 2019 - 2023 Jan Böhmer (https://github.com/jbtronics)
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as published
+ *  by the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+namespace App\Tests\Validator;
+
+use App\Validator\UniqueValidatableInterface;
+
+class DummyUniqueValidatableObject implements UniqueValidatableInterface, \Stringable
+{
+
+    public function __construct(public readonly array $array = [])
+    {
+    }
+
+    public function getComparableFields(): array
+    {
+        return $this->array;
+    }
+
+    public function __toString(): string
+    {
+        return 'objectString';
+    }
+}