Fix test purpose

tests/Doctrine/Tests/DBAL/ConnectionTest.php

@@ -403,22 +403,13 @@ SQLSTATE[HY000]: General error: 1 near \"MUUHAAAAHAAAA\"");
         $this->assertSame($result, $conn->fetchColumn($statement, $params, $column, $types));
     }
 
+    /**
+     * @expectedException Doctrine\DBAL\Exception\DriverException
+     */
     public function testConnectionIsClosed()
     {
-        $reflection = new \ReflectionObject($this->_conn);
-        $connProperty = $reflection->getProperty('_conn');
-        $connProperty->setAccessible(true);
-        $connProperty->setValue($this->_conn, new \stdClass);
-        
-        $connValue = $connProperty->getValue($this->_conn);
-        
-        $this->assertInstanceOf('stdClass', $connValue);
-        
         $this->_conn->close();
-        
-        $connNewValue = $connProperty->getValue($this->_conn);
-        
-        $this->assertNull($connNewValue, 'Connection can\'t be closed.');
+        $this->_conn->quoteIdentifier('Bug');
     }
 
     public function testFetchAll()