Fixing the problem with order and \Zend\Db\Sql\Expression

library/Zend/Db/Sql/Select.php

@@ -340,6 +340,8 @@ public function order($order)
             } else {
                 $order = (array) $order;
             }
+        } elseif ($order instanceof Expression){
+            $order = array($order);
         }
         foreach ($order as $k => $v) {
             if (is_string($k)) {

tests/ZendTest/Db/Sql/SelectTest.php

@@ -260,6 +260,10 @@ public function testOrder()
         $select = new Select;
         $select->order(array('name ASC', 'age DESC'));
         $this->assertEquals(array('name ASC', 'age DESC'), $select->getRawState('order'));
+
+        $select = new Select;
+        $select->order(new \Zend\db\sql\Expression('id DESC'));
+        $this->assertEquals('id DESC', current($select->getRawState('order'))->getExpression());
     }
 
     /**