Check if property is initialized before getting its value

This commit also removed the use of "setAccessible", since it's not
neccessary after PHP 8.1.

Co-authored-by: Henrique Moody <henriquemoody@gmail.com>

CHANGELOG.md

@@ -17,6 +17,7 @@ Fixes:
  - `KeySet` now reports which extra keys are causing the rule to fail.
  - Ensure empty strings are never a valid currency code
  - Do not hide messages on EachException
+ - Dot not throw exception when validating an uninitialized property
 
 Changes:
 

library/Rules/Attribute.php

@@ -17,7 +17,7 @@ use function is_object;
 use function property_exists;
 
 /**
- * Validates an object attribute, event private ones.
+ * Validates an object attribute, even private ones.
  *
  * @author Alexandre Gomes Gaigalas <alganet@gmail.com>
  * @author Emmerson Siqueira <emmersonsiqueira@gmail.com>
@@ -38,7 +38,9 @@ final class Attribute extends AbstractRelated
     public function getReferenceValue($input)
     {
         $propertyMirror = new ReflectionProperty($input, (string) $this->getReference());
-        $propertyMirror->setAccessible(true);
+        if ($propertyMirror->isInitialized($input) === false) {
+            return null;
+        }
 
         return $propertyMirror->getValue($input);
     }

tests/library/Stubs/WithUninitialized.php

@@ -0,0 +1,17 @@
+<?php
+
+/*
+ * Copyright (c) Alexandre Gomes Gaigalas <alganet@gmail.com>
+ * SPDX-License-Identifier: MIT
+ */
+
+declare(strict_types=1);
+
+namespace Respect\Validation\Test\Stubs;
+
+final class WithUninitialized
+{
+    public string $initialized = 'foo';
+
+    public string $uninitialized;
+}

tests/unit/Rules/AttributeTest.php

@@ -11,6 +11,7 @@ namespace Respect\Validation\Rules;
 
 use Respect\Validation\Test\RuleTestCase;
 use Respect\Validation\Test\Stubs\WithProperties;
+use Respect\Validation\Test\Stubs\WithUninitialized;
 
 /**
  * @group rule
@@ -47,6 +48,10 @@ final class AttributeTest extends RuleTestCase
                 new Attribute('public', new AlwaysValid()),
                 new WithProperties(),
             ],
+            'attribute is present but uninitialized' => [
+                new Attribute('uninitialized'),
+                new WithUninitialized(),
+            ],
             'non mandatory attribute is not present' => [
                 new Attribute('nonexistent', null, false),
                 new WithProperties(),
@@ -55,6 +60,10 @@ final class AttributeTest extends RuleTestCase
                 new Attribute('nonexistent', new AlwaysValid(), false),
                 new WithProperties(),
             ],
+            'attribute is present but uninitialized with extra validator' => [
+                new Attribute('uninitialized', new AlwaysValid()),
+                new WithUninitialized(),
+            ],
         ];
     }