[BUGFIX] Handle PHP Enum as tag attribute value (#1007)

It is now possible to provide PHP enums as value for additional tag attributes in tag-based ViewHelpers.

src/Core/ViewHelper/TagBuilder.php

@@ -173,7 +173,7 @@ public function ignoreEmptyAttributes(bool $ignoreEmptyAttributes): void
      *
      * @param string $attributeName name of the attribute to be added to the tag. Be extremely
      *                              careful if this value is user-provided input!
-     * @param string|bool|\Traversable|array|null $attributeValue attribute value, can only be array or traversable
+     * @param string|bool|\Traversable|array|\UnitEnum|\BackedEnum|null $attributeValue attribute value, can only be array or traversable
      *                                                       if the attribute name is either "data" or "area". In
      *                                                       that special case, multiple attributes will be created
      *                                                       with either "data-" or "area-" as prefix
@@ -223,6 +223,12 @@ public function addAttribute(string $attributeName, $attributeValue, bool $escap
                 $attributeValue = $attributeName;
             }
 
+            if ($attributeValue instanceof \BackedEnum) {
+                $attributeValue = (string)$attributeValue->value;
+            } elseif ($attributeValue instanceof \UnitEnum) {
+                $attributeValue = $attributeValue->name;
+            }
+
             if (trim((string)$attributeValue) === '' && $this->ignoreEmptyAttributes) {
                 return;
             }

tests/Functional/Core/ViewHelper/TagBasedViewHelperTest.php

@@ -12,6 +12,8 @@
 use PHPUnit\Framework\Attributes\DataProvider;
 use PHPUnit\Framework\Attributes\Test;
 use TYPO3Fluid\Fluid\Tests\Functional\AbstractFunctionalTestCase;
+use TYPO3Fluid\Fluid\Tests\Unit\Core\Variables\Fixtures\UserRoleBackedEnum;
+use TYPO3Fluid\Fluid\Tests\Unit\Core\Variables\Fixtures\UserRoleEnum;
 use TYPO3Fluid\Fluid\View\TemplateView;
 
 final class TagBasedViewHelperTest extends AbstractFunctionalTestCase
@@ -257,6 +259,15 @@ public static function renderTagBasedViewHelperDataProvider(): array
                 [],
                 '<div data-foo="attribute" />',
             ],
+            'enum attribute value' => [
+                '<test:tagBasedTest userRole="{userRole}" userRoleBacked="{userRoleBacked}" />',
+                '{test:tagBasedTest(userRole: userRole, userRoleBacked: userRoleBacked)}',
+                [
+                    'userRole' => UserRoleEnum::GUEST,
+                    'userRoleBacked' => UserRoleBackedEnum::EDITOR,
+                ],
+                '<div userRole="GUEST" userRoleBacked="2" />',
+            ],
         ];
     }
 

tests/Unit/Core/Variables/Fixtures/UserRoleBackedEnum.php

@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file belongs to the package "TYPO3 Fluid".
+ * See LICENSE.txt that was shipped with this package.
+ */
+
+namespace TYPO3Fluid\Fluid\Tests\Unit\Core\Variables\Fixtures;
+
+enum UserRoleBackedEnum: int
+{
+    case ADMIN = 1;
+    case EDITOR = 2;
+    case GUEST = 3;
+}

tests/Unit/Core/Variables/Fixtures/UserRoleEnum.php

@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file belongs to the package "TYPO3 Fluid".
+ * See LICENSE.txt that was shipped with this package.
+ */
+
+namespace TYPO3Fluid\Fluid\Tests\Unit\Core\Variables\Fixtures;
+
+enum UserRoleEnum
+{
+    case ADMIN;
+    case EDITOR;
+    case GUEST;
+}

tests/Unit/Core/ViewHelper/TagBuilderTest.php

@@ -14,6 +14,8 @@
 use PHPUnit\Framework\Attributes\Test;
 use PHPUnit\Framework\TestCase;
 use TYPO3Fluid\Fluid\Core\ViewHelper\TagBuilder;
+use TYPO3Fluid\Fluid\Tests\Unit\Core\Variables\Fixtures\UserRoleBackedEnum;
+use TYPO3Fluid\Fluid\Tests\Unit\Core\Variables\Fixtures\UserRoleEnum;
 
 final class TagBuilderTest extends TestCase
 {
@@ -160,6 +162,15 @@ public function attributeValuesAreNotEscapedIfDisabled(): void
         self::assertEquals('<tag foo="<not to be escaped>" />', $tagBuilder->render());
     }
 
+    #[Test]
+    public function attributesSupportEnum(): void
+    {
+        $tagBuilder = new TagBuilder('tag');
+        $tagBuilder->addAttribute('attribute1', UserRoleEnum::GUEST);
+        $tagBuilder->addAttribute('attribute2', UserRoleBackedEnum::GUEST);
+        self::assertEquals('<tag attribute1="GUEST" attribute2="3" />', $tagBuilder->render());
+    }
+
     #[Test]
     public function attributesCanBeRemoved(): void
     {