Implemented tests for relation

application/tests/Unit/Entity/Meta/RelationTest.php

@@ -0,0 +1,28 @@
+<?php
+namespace tests\Unit\Entity\Meta;
+
+use PHPUnit\Framework\TestCase;
+use App\Entity\Meta\RelationInterface;
+use App\Entity\Meta\Relation;
+use Doctrine\Common\Collections\Collection;
+
+class RelationTest extends TestCase
+{
+    /**
+     * 
+     * @var RelationInterface
+     */
+    protected $relation;
+    
+    public function setUp():void{
+        $this->relation = new Relation();
+    }
+    
+    public function testConstructor():void {
+        $this->assertInstanceOf(Collection::class, $this->relation->getChilds());
+        $this->assertInstanceOf(Collection::class, $this->relation->getParents());
+        $this->expectException(\TypeError::class);
+        $this->relation->getSource();
+    }
+}
+