test for addSelect method.

tests/unit/framework/db/QueryTest.php

@@ -24,6 +24,11 @@ class QueryTest extends DatabaseTestCase
         $this->assertEquals(['id', 'name'], $query->select);
         $this->assertTrue($query->distinct);
         $this->assertEquals('something', $query->selectOption);
+        
+        $query = new Query();
+        $query->select('id, name');
+        $query->addSelect('email');
+        $this->assertEquals(['id', 'name', 'email'], $query->select);
     }
 
     public function testFrom()