[TASK] Add Rector script and configuration (#56)

composer.json

@@ -102,8 +102,14 @@
 		],
 		"fix:composer:normalize": "@composer normalize",
 		"fix:php": [
+			"@fix:php:rector",
 			"@fix:php:cs"
 		],
-		"fix:php:cs": "php-cs-fixer fix"
+		"fix:php:cs": "php-cs-fixer fix",
+		"fix:php:rector": [
+			"@composer require --dev rector/rector",
+			"@php rector process",
+			"@composer remove --dev rector/rector"
+		]
 	}
 }

rector.php

@@ -0,0 +1,61 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the TYPO3 project.
+ *
+ * (c) 2019-2022 Benni Mack
+ *               Simon Gilli
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ *
+ * The TYPO3 project - inspiring people to share!
+ */
+
+use Rector\Config\RectorConfig;
+use Rector\PHPUnit\Set\PHPUnitLevelSetList;
+use Rector\PHPUnit\Set\PHPUnitSetList;
+use Rector\Privatization\Rector\Class_\FinalizeClassesWithoutChildrenRector;
+use Rector\Set\ValueObject\DowngradeLevelSetList;
+use Rector\Set\ValueObject\LevelSetList;
+use Rector\Set\ValueObject\SetList;
+
+return static function (RectorConfig $rectorConfig): void {
+    $rectorConfig->paths([
+        __DIR__ . '/src',
+        __DIR__ . '/tests',
+    ]);
+
+    $rectorConfig->skip([
+        __DIR__ . '/tests/Unit/Fixtures',
+
+        FinalizeClassesWithoutChildrenRector::class => [
+            __DIR__ . '/src/CsFixerConfig.php',
+        ],
+    ]);
+
+    // define sets of rules
+    $rectorConfig->sets([
+        LevelSetList::UP_TO_PHP_72,
+        DowngradeLevelSetList::DOWN_TO_PHP_72,
+        SetList::CODE_QUALITY,
+        SetList::CODING_STYLE,
+        SetList::DEAD_CODE,
+        SetList::NAMING,
+        SetList::PRIVATIZATION,
+        SetList::PSR_4,
+        SetList::TYPE_DECLARATION,
+        SetList::TYPE_DECLARATION_STRICT,
+        SetList::EARLY_RETURN,
+
+        // PHPUnit rules
+        PHPUnitLevelSetList::UP_TO_PHPUNIT_80,
+        PHPUnitSetList::PHPUNIT_CODE_QUALITY,
+        PHPUnitSetList::PHPUNIT_EXCEPTION,
+        PHPUnitSetList::REMOVE_MOCKS,
+        PHPUnitSetList::PHPUNIT_SPECIFIC_METHOD,
+        PHPUnitSetList::PHPUNIT_YIELD_DATA_PROVIDER,
+    ]);
+};