Added logic to resolve crawlable short codes

module/Core/test/Crawling/CrawlingHelperTest.php

@@ -0,0 +1,43 @@
+<?php
+
+declare(strict_types=1);
+
+namespace ShlinkioTest\Shlink\Core\Crawling;
+
+use Doctrine\ORM\EntityManagerInterface;
+use PHPUnit\Framework\TestCase;
+use Prophecy\PhpUnit\ProphecyTrait;
+use Prophecy\Prophecy\ObjectProphecy;
+use Shlinkio\Shlink\Core\Crawling\CrawlingHelper;
+use Shlinkio\Shlink\Core\Entity\ShortUrl;
+use Shlinkio\Shlink\Core\Repository\ShortUrlRepositoryInterface;
+
+class CrawlingHelperTest extends TestCase
+{
+    use ProphecyTrait;
+
+    private CrawlingHelper $helper;
+    private ObjectProphecy $em;
+
+    protected function setUp(): void
+    {
+        $this->em = $this->prophesize(EntityManagerInterface::class);
+        $this->helper = new CrawlingHelper($this->em->reveal());
+    }
+
+    /** @test */
+    public function listCrawlableShortCodesDelegatesIntoRepository(): void
+    {
+        $repo = $this->prophesize(ShortUrlRepositoryInterface::class);
+        $findCrawlableShortCodes = $repo->findCrawlableShortCodes()->willReturn([]);
+        $getRepo = $this->em->getRepository(ShortUrl::class)->willReturn($repo->reveal());
+
+        $result = $this->helper->listCrawlableShortCodes();
+        foreach ($result as $shortCode) {
+            // Result is a generator and therefore, it needs to be iterated
+        }
+
+        $findCrawlableShortCodes->shouldHaveBeenCalledOnce();
+        $getRepo->shouldHaveBeenCalledOnce();
+    }
+}