Add tag factory into tests

[MAILPOET-4440]

mailpoet/tests/DataFactories/Tag.php

@@ -0,0 +1,47 @@
+<?php declare(strict_types = 1);
+
+namespace MailPoet\Test\DataFactories;
+
+use MailPoet\DI\ContainerWrapper;
+use MailPoet\Entities\TagEntity;
+use MailPoet\Tags\TagRepository;
+
+class Tag {
+  /** @var array */
+  private $data;
+
+  /** @var TagRepository */
+  private $tagRepository;
+
+  public function __construct() {
+    $this->tagRepository = ContainerWrapper::getInstance()->get(TagRepository::class);
+    $this->data = [
+      'name' => 'Tag' . bin2hex(random_bytes(7)),
+    ];
+  }
+
+  /**
+   * @return $this
+   */
+  public function withName(string $name) {
+    return $this->update('name', $name);
+  }
+
+  public function create(): TagEntity {
+    $tag = new TagEntity($this->data['name']);
+    $this->tagRepository->persist($tag);
+    $this->tagRepository->flush();
+    return $tag;
+  }
+
+  /**
+   * @return $this
+   */
+  private function update(string $item, $value) {
+    $data = $this->data;
+    $data[$item] = $value;
+    $new = clone $this;
+    $new->data = $data;
+    return $new;
+  }
+}