Extract a method to contain the query logic

Group all of the query logic into one method, as this will make it more
readable and this logic is likely to grow.

References #3

web/modules/custom/blog/src/Repository/RelatedPostsRepository.php

@@ -6,6 +6,7 @@ namespace Drupal\opdavies_blog\Repository;
 
 use Drupal\Core\Entity\EntityStorageInterface;
 use Drupal\Core\Entity\EntityTypeManagerInterface;
+use Drupal\Core\Entity\Query\QueryInterface;
 use Drupal\opdavies_blog\Entity\Node\Post;
 use Drupal\taxonomy\TermInterface;
 use Illuminate\Support\Collection;
@@ -31,19 +32,24 @@ final class RelatedPostsRepository {
       ->map(fn(TermInterface $tag) => $tag->id())
       ->values();
 
+    /** @var array $postIds */
+    $postIds = $this->query($post, $tagIds)->execute();
+
+    $posts = $this->nodeStorage->loadMultiple($postIds);
+
+    return new Collection(array_values($posts));
+  }
+
+  private function query(Post $post, Collection $tagIds): QueryInterface {
     $query = $this->nodeStorage->getQuery();
 
     // Ensure that the current node ID is not returned as a related post.
     $query->condition('nid', $post->id(), '!=');
 
+    // Only return posts with the same tags.
     $query->condition('field_tags', $tagIds->toArray(), 'IN');
 
-    /** @var array $postIds */
-    $postIds = $query->execute();
-
-    $posts = $this->nodeStorage->loadMultiple($postIds);
-
-    return (new Collection($posts))->values();
+    return $query;
   }
 
 }