MAGETWO-96534: Changing random string generation

Author: Mark Berube

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

@@ -5,9 +5,13 @@
  */
 namespace Magento\Captcha\Model;
 
+use Magento\Framework\Math\Random;
+
 /**
  * Implementation of \Zend_Captcha
  *
+ * @SuppressWarnings(PHPMD.CookieAndSessionMisuse)
+ *
  * @author     Magento Core Team <core@magentocommerce.com>
  */
 class DefaultModel extends \Zend_Captcha_Image implements \Magento\Captcha\Model\CaptchaInterface
@@ -68,22 +72,30 @@ class DefaultModel extends \Zend_Captcha_Image implements \Magento\Captcha\Model
      */
     protected $_session;
 
+    /**
+     * @var Random
+     */
+    private $randomMath;
+
     /**
      * @param \Magento\Framework\Session\SessionManagerInterface $session
      * @param \Magento\Captcha\Helper\Data $captchaData
      * @param \Magento\Captcha\Model\ResourceModel\LogFactory $resLogFactory
+     * @param Random $randomMath
      * @param string $formId
      */
     public function __construct(
         \Magento\Framework\Session\SessionManagerInterface $session,
         \Magento\Captcha\Helper\Data $captchaData,
         \Magento\Captcha\Model\ResourceModel\LogFactory $resLogFactory,
-        $formId
+        $formId,
+        Random $randomMath = null
     ) {
         $this->_session = $session;
         $this->_captchaData = $captchaData;
         $this->_resLogFactory = $resLogFactory;
         $this->_formId = $formId;
+        $this->randomMath = $randomMath ?: \Magento\Framework\App\ObjectManager::getInstance()->get(Random::class);
     }
 
     /**
@@ -361,23 +373,9 @@ 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 $word;
-    }
-
-    /**
-     * Get symbols array to use for word generation
-     *
-     * @return array
-     */
-    protected function _getSymbols()
-    {
-        return str_split((string)$this->_captchaData->getConfig('symbols'));
+        return $this->randomMath->getRandomString($wordLen, $symbols);
     }
 
     /**

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

@@ -376,4 +376,41 @@ public function isShownToLoggedInUserDataProvider()
             [false, 'guest_checkout']
         ];
     }
+
+    /**
+     * @param string $string
+     * @dataProvider GenerateWordProvider
+     * @throws \ReflectionException
+     */
+    public function testGenerateWord($string)
+    {
+        $randomMock = $this->getMock('Magento\Framework\Math\Random');
+        $randomMock->expects($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.']
+        ];
+    }
 }