Allow _prefix in symfony coding standard

src/Rules/File/FileNameRule.php

@@ -27,6 +27,7 @@ public function __construct(
         private string $case = self::SNAKE_CASE,
         private ?string $baseDirectory = null,
         private array $ignoredSubDirectories = [],
+        private string $allowedPrefix = '',
     ) {
     }
 
@@ -36,6 +37,7 @@ public function getConfiguration(): array
             'case' => $this->case,
             'baseDirectory' => $this->baseDirectory,
             'ignoredSubDirectories' => $this->ignoredSubDirectories,
+            'allowedPrefix' => $this->allowedPrefix,
         ];
     }
 
@@ -59,6 +61,12 @@ protected function process(int $tokenPosition, array $tokens): void
         // in order to avoid conflict with some file extensions.
         $fileName = explode('.', FileHelper::removeDot($fileName))[0];
 
+        $prefix = '';
+        if (str_starts_with($fileName, $this->allowedPrefix)) {
+            $prefix = $this->allowedPrefix;
+            $fileName = substr($fileName, \strlen($this->allowedPrefix));
+        }
+
         $expected = match ($this->case) {
             self::SNAKE_CASE => StringUtil::toSnakeCase($fileName),
             self::CAMEL_CASE => StringUtil::toCamelCase($fileName),
@@ -68,7 +76,7 @@ protected function process(int $tokenPosition, array $tokens): void
 
         if ($expected !== $fileName) {
             $this->addFileError(
-                sprintf('The file name must use %s; expected %s.', $this->case, $expected),
+                sprintf('The file name must use %s; expected %s.', $this->case, $prefix.$expected),
                 $token,
             );
         }

src/Standard/Symfony.php

@@ -13,14 +13,15 @@
  *
  * @see https://twig.symfony.com/doc/3.x/coding_standards.html
  * @see https://symfony.com/doc/current/templates.html#template-naming
+ * @see https://symfony.com/doc/current/best_practices.html#templates
  */
 final class Symfony implements StandardInterface
 {
     public function getRules(): array
     {
         return [
             ...(new Twig())->getRules(),
-            new FileNameRule(baseDirectory: 'templates', ignoredSubDirectories: ['bundles']),
+            new FileNameRule(baseDirectory: 'templates', ignoredSubDirectories: ['bundles'], allowedPrefix: '_'),
             new DirectoryNameRule(baseDirectory: 'templates', ignoredSubDirectories: ['bundles']),
             new FileExtensionRule(),
         ];

tests/Rules/File/FileName/FileNameRuleTest.php

@@ -89,4 +89,10 @@ public function testRuleIgnoredPath(): void
     {
         $this->checkRule(new FileNameRule(baseDirectory: __DIR__.'/..', ignoredSubDirectories: ['FileName']), []);
     }
+
+    public function testRuleAllowedPrefix(): void
+    {
+        $this->checkRule(new FileNameRule(), ['FileName.Error'], __DIR__.'/_file_name_rule_test.twig');
+        $this->checkRule(new FileNameRule(allowedPrefix: '_'), [], __DIR__.'/_file_name_rule_test.twig');
+    }
 }

tests/Rules/File/FileName/_file_name_rule_test.twig

@@ -0,0 +1 @@
+Nothing