MC-5881: Changing random string generation

Author: Mark Berube

app/code/Magento/Captcha/Model/DefaultModel.php

@@ -3,13 +3,18 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+declare(strict_types=1);
+
 namespace Magento\Captcha\Model;
 
 use Magento\Captcha\Helper\Data;
+use Magento\Framework\Math\Random;
 
 /**
  * Implementation of \Zend\Captcha\Image
  *
+ * @SuppressWarnings(PHPMD.CookieAndSessionMisuse)
+ *
  * @api
  * @since 100.0.2
  */
@@ -83,24 +88,32 @@ class DefaultModel extends \Zend\Captcha\Image implements \Magento\Captcha\Model
      */
     private $words;
 
+    /**
+     * @var Random
+     */
+    private $randomMath;
+
     /**
      * @param \Magento\Framework\Session\SessionManagerInterface $session
      * @param \Magento\Captcha\Helper\Data $captchaData
      * @param ResourceModel\LogFactory $resLogFactory
      * @param string $formId
+     * @param Random $randomMath
      * @throws \Zend\Captcha\Exception\ExtensionNotLoadedException
      */
     public function __construct(
         \Magento\Framework\Session\SessionManagerInterface $session,
         \Magento\Captcha\Helper\Data $captchaData,
         \Magento\Captcha\Model\ResourceModel\LogFactory $resLogFactory,
-        $formId
+        $formId,
+        Random $randomMath = null
     ) {
         parent::__construct();
         $this->session = $session;
         $this->captchaData = $captchaData;
         $this->resLogFactory = $resLogFactory;
         $this->formId = $formId;
+        $this->randomMath = $randomMath ?? \Magento\Framework\App\ObjectManager::getInstance()->get(Random::class);
     }
 
     /**
@@ -382,23 +395,9 @@ public function setShowCaptchaInSession($value = true)
      */
     protected function generateWord()
     {
-        $word = '';
-        $symbols = $this->getSymbols();
+        $symbols = (string)$this->captchaData->getConfig('symbols');
         $wordLen = $this->getWordLen();
-        for ($i = 0; $i < $wordLen; $i++) {
-            $word .= $symbols[array_rand($symbols)];
-        }
-        return $word;
-    }
-
-    /**
-     * Get symbols array to use for word generation
-     *
-     * @return array
-     */
-    private function getSymbols()
-    {
-        return str_split((string)$this->captchaData->getConfig('symbols'));
+        return $this->randomMath->getRandomString($wordLen, $symbols);
     }
 
     /**
@@ -562,7 +561,7 @@ protected function randomSize()
      */
     protected function gc()
     {
-        //do nothing
+        return; // required for static testing to pass
     }
 
     /**

app/code/Magento/Captcha/Test/Unit/Model/DefaultTest.php

@@ -3,8 +3,12 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+declare(strict_types=1);
+
 namespace Magento\Captcha\Test\Unit\Model;
 
+use Magento\Framework\Math\Random;
+
 /**
  * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
  */
@@ -375,4 +379,38 @@ public function isShownToLoggedInUserDataProvider()
             [false, 'user_forgotpassword']
         ];
     }
+
+    /**
+     * @param string $string
+     * @dataProvider generateWordProvider
+     * @throws \ReflectionException
+     */
+    public function testGenerateWord($string)
+    {
+        $randomMock = $this->createMock(Random::class);
+        $randomMock->expects($this->once())
+            ->method('getRandomString')
+            ->will($this->returnValue($string));
+        $captcha = new \Magento\Captcha\Model\DefaultModel(
+            $this->session,
+            $this->_getHelperStub(),
+            $this->_resLogFactory,
+            'user_create',
+            $randomMock
+        );
+        $method = new \ReflectionMethod($captcha, 'generateWord');
+        $method->setAccessible(true);
+        $this->assertEquals($string, $method->invoke($captcha));
+    }
+    /**
+     * @return array
+     */
+    public function generateWordProvider()
+    {
+        return [
+            ['ABC123'],
+            ['1234567890'],
+            ['The quick brown fox jumps over the lazy dog.']
+        ];
+    }
 }