Actualización

vendor/symfony/form/Tests/CallbackTransformerTest.php

@@ -0,0 +1,29 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Form\Tests;
+
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Form\CallbackTransformer;
+
+class CallbackTransformerTest extends TestCase
+{
+    public function testTransform()
+    {
+        $transformer = new CallbackTransformer(
+            function ($value) { return $value.' has been transformed'; },
+            function ($value) { return $value.' has reversely been transformed'; }
+        );
+
+        $this->assertEquals('foo has been transformed', $transformer->transform('foo'));
+        $this->assertEquals('bar has reversely been transformed', $transformer->reverseTransform('bar'));
+    }
+}