Fixed issue on GroupBy clause

Author: dalibert42

src/SQLParser/Query/Select.php

@@ -350,7 +350,7 @@ public function toSql(array $parameters = array(), Connection $dbConnection = nu
         }
 
         if (!empty($this->group)) {
-            $groupBy = NodeFactory::toSql($this->group, $dbConnection, $parameters, ' ', false, $indent + 2, $conditionsMode);
+            $groupBy = NodeFactory::toSql($this->group, $dbConnection, $parameters, ',', false, $indent + 2, $conditionsMode);
             if ($groupBy) {
                 $sql .= "\nGROUP BY ".$groupBy;
             }

tests/Mouf/Database/MagicQueryTest.php

@@ -104,6 +104,9 @@ public function testStandardSelect()
 
         $sql = 'SELECT * FROM users WHERE status IN :statuses!';
         $this->assertEquals('SELECT * FROM users WHERE FALSE', self::simplifySql($magicQuery->build($sql, ['statuses' => []])));
+
+        $sql = 'SELECT * FROM users GROUP BY id, login';
+        $this->assertEquals('SELECT * FROM users GROUP BY id, login', self::simplifySql($magicQuery->build($sql)));
     }
 
     /**