Add tests with the examples given in the PR

tests/Doctrine/Tests/ORM/Functional/Ticket/GH10913Test.php

@@ -0,0 +1,167 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\Tests\ORM\Functional\Ticket;
+
+use Doctrine\ORM\Internal\TopologicalSort\CycleDetectedException;
+use Doctrine\ORM\Mapping as ORM;
+use Doctrine\Tests\OrmFunctionalTestCase;
+
+use function array_filter;
+use function array_values;
+use function strpos;
+
+class GH10913Test extends OrmFunctionalTestCase
+{
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->setUpEntitySchema([
+            GH10913Entity::class,
+        ]);
+    }
+
+    public function testExample1(): void
+    {
+        [$a, $b, $c] = $this->createEntities(3);
+
+        $c->ref = $b;
+        $b->odc = $a;
+
+        $this->_em->persist($a);
+        $this->_em->persist($b);
+        $this->_em->persist($c);
+        $this->_em->flush();
+
+        $this->_em->remove($a);
+        $this->_em->remove($b);
+        $this->_em->remove($c);
+
+        $this->flushAndAssertNumberOfDeleteQueries(3);
+    }
+
+    public function testExample2(): void
+    {
+        [$a, $b, $c] = $this->createEntities(3);
+
+        $a->odc = $b;
+        $b->odc = $a;
+        $c->ref = $b;
+
+        $this->_em->persist($a);
+        $this->_em->persist($b);
+        $this->_em->persist($c);
+        $this->_em->flush();
+
+        $this->_em->remove($a);
+        $this->_em->remove($b);
+        $this->_em->remove($c);
+
+        $this->flushAndAssertNumberOfDeleteQueries(3);
+    }
+
+    public function testExample3(): void
+    {
+        [$a, $b, $c] = $this->createEntities(3);
+
+        $a->odc = $b;
+        $a->ref = $c;
+        $c->ref = $b;
+        $b->odc = $a;
+
+        $this->_em->persist($a);
+        $this->_em->persist($b);
+        $this->_em->persist($c);
+        $this->_em->flush();
+
+        $this->_em->remove($a);
+        $this->_em->remove($b);
+        $this->_em->remove($c);
+
+        self::expectException(CycleDetectedException::class);
+
+        $this->_em->flush();
+    }
+
+    public function testExample4(): void
+    {
+        [$a, $b, $c, $d] = $this->createEntities(4);
+
+        $a->ref = $b;
+        $b->odc = $c;
+        $c->odc = $b;
+        $d->ref = $c;
+
+        $this->_em->persist($a);
+        $this->_em->persist($b);
+        $this->_em->persist($c);
+        $this->_em->persist($d);
+        $this->_em->flush();
+
+        $this->_em->remove($b);
+        $this->_em->remove($c);
+        $this->_em->remove($d);
+        $this->_em->remove($a);
+
+        $this->flushAndAssertNumberOfDeleteQueries(4);
+    }
+
+    private function flushAndAssertNumberOfDeleteQueries(int $expectedCount): void
+    {
+        $queryLog = $this->getQueryLog();
+        $queryLog->reset()->enable();
+
+        $this->_em->flush();
+
+        $queries = array_values(array_filter($queryLog->queries, static function ($entry) {
+            return strpos($entry['sql'], 'DELETE') === 0;
+        }));
+
+        self::assertCount($expectedCount, $queries);
+    }
+
+    /**
+     * @return list<GH10913Entity>
+     */
+    private function createEntities(int $count = 1): array
+    {
+        $result = [];
+
+        for ($i = 0; $i < $count; $i++) {
+            $result[] = new GH10913Entity();
+        }
+
+        return $result;
+    }
+}
+
+/** @ORM\Entity */
+class GH10913Entity
+{
+    /**
+     * @ORM\Id
+     * @ORM\Column(type="integer")
+     * @ORM\GeneratedValue
+     *
+     * @var int
+     */
+    public $id;
+
+    /**
+     * @ORM\ManyToOne(targetEntity=GH10913Entity::class)
+     * @ORM\JoinColumn(nullable=true, onDelete="CASCADE")
+     *
+     * @var GH10913Entity
+     */
+    public $odc;
+
+    /**
+     * @ORM\ManyToOne(targetEntity=GH10913Entity::class)
+     * @ORM\JoinColumn(nullable=true)
+     *
+     * @var GH10913Entity
+     */
+    public $ref;
+}