Index: Zend/Captcha/FigletTest.php
===================================================================
--- Zend/Captcha/FigletTest.php	(revision 11805)
+++ Zend/Captcha/FigletTest.php	(working copy)
@@ -243,6 +243,23 @@
                       ->setWordLen(14);
         $id = $this->captcha->generate();
     }
+    public function testShouldNotValidateEmptyInputAgainstEmptySession()
+    {
+    	// Regression Test for ZF-4245
+    	$this->captcha->setName('foo')
+    	              ->setWordLen(6)
+    	              ->setTimeout(300);
+    	$id = $this->captcha->generate();
+    	// Unset the generated word
+    	// we have to reset $this->captcha for that
+    	$this->captcha->getSession()->word = null;
+    	$this->setUp();
+    	$this->captcha->setName('foo')
+    	              ->setWordLen(6)
+    	              ->setTimeout(300);
+    	$empty = array($this->captcha->getName() => array('id' => $id, 'input' => ''));
+    	$this->assertEquals(false, $this->captcha->isValid(null, $empty));
+    }
 }
 
 class Zend_Captcha_FigletTest_SessionContainer