feat: offer a newsletter opt-in for the other participants

addresses #869etn6c5

tests/Form/BookingCreateStep4TypeTest.php

@@ -0,0 +1,58 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Tests\Form;
+
+use App\BusProNet\Model\Travel;
+use App\Form\BookingCreateStep4Type;
+use App\Form\Model\BookingDto;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Form\Extension\Validator\ValidatorExtension;
+use Symfony\Component\Form\FormInterface;
+use Symfony\Component\Form\Forms;
+use Symfony\Component\Form\PreloadedExtension;
+use Symfony\Component\Validator\Validation;
+
+class BookingCreateStep4TypeTest extends TestCase
+{
+    public function testCompanionOptInIsAbsentByDefault(): void
+    {
+        $form = $this->createForm();
+
+        self::assertFalse($form->has('companionNewsletterOptIn'));
+    }
+
+    public function testCompanionOptInIsAddedWhenTheOptionIsOn(): void
+    {
+        $form = $this->createForm(['show_companion_newsletter_opt_in' => true]);
+
+        self::assertTrue($form->has('companionNewsletterOptIn'));
+        self::assertFalse($form->get('companionNewsletterOptIn')->isRequired());
+    }
+
+    public function testCompanionOptInIsIndependentOfTheApplicantOptIn(): void
+    {
+        $form = $this->createForm(['show_companion_newsletter_opt_in' => true]);
+
+        self::assertFalse($form->has('newsletterOptIn'));
+        self::assertTrue($form->has('companionNewsletterOptIn'));
+    }
+
+    /**
+     * @param array<string, mixed> $options
+     *
+     * @return FormInterface<mixed>
+     */
+    private function createForm(array $options = []): FormInterface
+    {
+        $travel = new Travel();
+        $travel->id = 123;
+
+        return Forms::createFormFactoryBuilder()
+            ->addExtension(new ValidatorExtension(Validation::createValidator()))
+            ->addExtension(new PreloadedExtension([new BookingCreateStep4Type('https://example.com/agb')], []))
+            ->getFormFactory()
+            ->create(BookingCreateStep4Type::class, new BookingDto($travel, 77), $options);
+    }
+}