Extract the CardTypeDataTransformer from the TpayCardType

config/services/form.php

@@ -4,6 +4,7 @@
 
 namespace Symfony\Component\DependencyInjection\Loader\Configurator;
 
+use CommerceWeavers\SyliusTpayPlugin\Form\DataTransformer\CardTypeDataTransformer;
 use CommerceWeavers\SyliusTpayPlugin\Form\EventListener\PreventSavingEmptyClientSecretListener;
 use CommerceWeavers\SyliusTpayPlugin\Form\Extension\CompleteTypeExtension;
 use CommerceWeavers\SyliusTpayPlugin\Form\Type\TpayCardType;
@@ -14,6 +15,8 @@
 return function(ContainerConfigurator $container): void {
     $services = $container->services();
 
+    $services->set('commerce_weavers_tpay.form.data_transformer.card_type', CardTypeDataTransformer::class);
+
     $services->set(CompleteTypeExtension::class)
         ->tag('form.type_extension')
     ;
@@ -29,7 +32,12 @@
         ->tag('form.type')
     ;
 
-    $services->set(TpayCardType::class)->tag('form.type');
+    $services->set(TpayCardType::class)
+        ->args([
+            service('commerce_weavers_tpay.form.data_transformer.card_type'),
+        ])
+        ->tag('form.type')
+    ;
 
     $services->set(TpayPaymentDetailsType::class)->tag('form.type');
 

phpstan.neon

@@ -15,3 +15,5 @@ parameters:
         - '/Parameter \#1 \$request \([^)]+\) of method [^:]+::execute\(\) should be contravariant with parameter \$request \(mixed\) of method Payum\\Core\\Action\\ActionInterface::execute\(\)/'
         - '/Parameter \$event of method CommerceWeavers\\SyliusTpayPlugin\\Refunding\\Workflow\\Listener\\DispatchRefundListener::__invoke\(\) has invalid type Symfony\\Component\\Workflow\\Event\\TransitionEvent\./'
         - '/Call to method getSubject\(\) on an unknown class Symfony\\Component\\Workflow\\Event\\TransitionEvent\./'
+        - '#Class CommerceWeavers\\SyliusTpayPlugin\\Form\\DataTransformer\\CardTypeDataTransformer implements generic interface Symfony\\Component\\Form\\DataTransformerInterface but does not specify its types: TValue, TTransformedValue#'
+        - '#Method CommerceWeavers\\SyliusTpayPlugin\\Form\\Type\\TpayCardType::__construct\(\) has parameter \$cardTypeDataTransformer with generic interface Symfony\\Component\\Form\\DataTransformerInterface but does not specify its types: TValue, TTransformedValue#'

src/Form/DataTransformer/CardTypeDataTransformer.php

@@ -0,0 +1,27 @@
+<?php
+
+declare(strict_types=1);
+
+namespace CommerceWeavers\SyliusTpayPlugin\Form\DataTransformer;
+
+use Symfony\Component\Form\DataTransformerInterface;
+
+final class CardTypeDataTransformer implements DataTransformerInterface
+{
+    public function transform($value): ?array
+    {
+        return null;
+    }
+
+    /**
+     * @param mixed|array{card: string} $value
+     */
+    public function reverseTransform(mixed $value): string
+    {
+        if (!is_array($value)) {
+            return '';
+        }
+
+        return $value['card'];
+    }
+}

src/Form/Type/TpayCardType.php

@@ -13,6 +13,11 @@
 
 final class TpayCardType extends AbstractType
 {
+    public function __construct(
+        private DataTransformerInterface $cardTypeDataTransformer,
+    ) {
+    }
+
     /**
      * @param array<string, mixed> $options
      */
@@ -76,24 +81,6 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             ->add('card', HiddenType::class)
         ;
 
-        /** TODO: Extract into a separate class */
-        $builder->addModelTransformer(new class() implements DataTransformerInterface {
-            public function transform($value): ?array
-            {
-                return null;
-            }
-
-            /**
-             * @param mixed|array{card: string} $value
-             */
-            public function reverseTransform(mixed $value): string
-            {
-                if (!is_array($value)) {
-                    return '';
-                }
-
-                return $value['card'];
-            }
-        });
+        $builder->addModelTransformer($this->cardTypeDataTransformer);
     }
 }

tests/Unit/Form/DataTransformer/CardTypeDataTransformerTest.php

@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\CommerceWeavers\SyliusTpayPlugin\Unit\Form\DataTransformer;
+
+use CommerceWeavers\SyliusTpayPlugin\Form\DataTransformer\CardTypeDataTransformer;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Form\DataTransformerInterface;
+
+final class CardTypeDataTransformerTest extends TestCase
+{
+    public function test_it_returns_null_on_a_transform(): void
+    {
+        $dataTransformer = $this->createTestSubject();
+
+        $this->assertSame(null, $dataTransformer->transform(null));
+        $this->assertSame(null, $dataTransformer->transform(true));
+        $this->assertSame(null, $dataTransformer->transform('string'));
+        $this->assertSame(null, $dataTransformer->transform(1));
+    }
+
+    public function test_it_returns_an_empty_string_when_trying_to_reverse_transform_a_non_array(): void
+    {
+        $dataTransformer = $this->createTestSubject();
+
+        $this->assertSame('', $dataTransformer->reverseTransform(null));
+        $this->assertSame('', $dataTransformer->reverseTransform(true));
+        $this->assertSame('', $dataTransformer->reverseTransform('string'));
+        $this->assertSame('', $dataTransformer->reverseTransform(1));
+    }
+
+    private function createTestSubject(): DataTransformerInterface
+    {
+        return new CardTypeDataTransformer();
+    }
+}