Fixed code by recommendation

Author: anzin

Magento2/Sniffs/Functions/DeprecatedFunctionSniff.php

@@ -0,0 +1,73 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento2\Sniffs\Functions;
+
+use PHP_CodeSniffer\Files\File;
+use PHP_CodeSniffer\Sniffs\Sniff;
+
+/**
+ * Sniff to validate PHP functions usage of which without passing arguments is deprecated.
+ */
+class FunctionsDeprecatedWithoutArgumentSniff implements Sniff
+{
+    /**
+     * String representation of warning.
+     *
+     * @var string
+     */
+    private $warningMessage = 'Calling function %s() without argument is deprecated in PHP 8.1. '
+        . 'Please pass the input to validate as the first argument of the function.';
+
+    /**
+     * Warning violation code.
+     *
+     * @var string
+     */
+    private $warningCode = 'DeprecatedFunction';
+
+    /**
+     * Deprecated functions without argument.
+     *
+     * @var array
+     */
+    private $deprecatedFunctions = [
+        'mb_check_encoding',
+        'get_class',
+        'get_parent_class',
+        'get_called_class'
+    ];
+
+    /**
+     * @inheritdoc
+     */
+    public function register(): array
+    {
+        return [
+            T_OPEN_PARENTHESIS
+        ];
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function process(File $phpcsFile, $stackPtr): void
+    {
+        $closeParenthesisPtr = $phpcsFile->findNext(T_CLOSE_PARENTHESIS, $stackPtr);
+        $arguments = trim($phpcsFile->getTokensAsString($stackPtr + 1, $closeParenthesisPtr - $stackPtr - 1));
+
+        if ($arguments) {
+            return;
+        }
+
+        $functionName = $phpcsFile->getTokensAsString($phpcsFile->findPrevious(T_STRING, $stackPtr), 1);
+
+        if (in_array($functionName, $this->deprecatedFunctions)) {
+            $phpcsFile->addWarning(sprintf($this->warningMessage, $functionName), $stackPtr, $this->warningCode);
+        }
+    }
+}

Magento2/Sniffs/Functions/FunctionsDeprecatedWithoutArgumentSniff.php

@@ -0,0 +1,33 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento2\Tests\Functions;
+
+/**
+ * Class to test validate PHP functions usage of which without passing arguments.
+ */
+class FunctionsDeprecatedWithoutArgument
+{
+    /**
+     * Test deprecation function.
+     *
+     * @return array
+     */
+    public function testDeprecatedMethod(): array
+    {
+        return [
+            mb_check_encoding(), // Calling without argument is deprecated.
+            mb_check_encoding('test-argument', null),
+            get_class(), // Calling without argument is deprecated.
+            get_class(new FunctionsDeprecatedWithoutArgument()),
+            get_parent_class(), // Calling without argument is deprecated.
+            get_parent_class('test-argument'),
+            get_called_class(), // Calling without argument is deprecated.
+            get_called_class('test-argument')
+        ];
+    }
+}

Magento2/Tests/Functions/DeprecatedFunctionUnitTest.inc

@@ -10,9 +10,9 @@
 use PHP_CodeSniffer\Tests\Standards\AbstractSniffUnitTest;
 
 /**
- * Sniff to validate PHP deprecated function.
+ * Test to validate PHP functions usage of which without passing arguments.
  */
-class DeprecatedFunctionUnitTest extends AbstractSniffUnitTest
+class FunctionsDeprecatedWithoutArgumentUnitTest extends AbstractSniffUnitTest
 {
     /**
      * @inheritdoc
@@ -25,14 +25,13 @@ public function getErrorList(): array
     /**
      * @inheritdoc
      */
-    public function getWarningList($testFile = ''): array
+    public function getWarningList(): array
     {
-        if ($testFile === 'DeprecatedFunctionUnitTest.inc') {
-            return [
-                23 => 1
-            ];
-        }
-
-        return [];
+        return [
+            23 => 1,
+            25 => 1,
+            27 => 1,
+            29 => 1
+        ];
     }
 }