public function testMergeGroupBy()
 {
     $this->queryBuilder->groupBy('id');
     $qb = new SelectQueryBuilder();
     $qb->groupBy('score', SelectQueryBuilder::ASC);
     $this->queryBuilder->mergeGroupBy($qb);
     $expected = array(array('column' => 'id', 'order' => NULL), array('column' => 'score', 'order' => SelectQueryBuilder::ASC));
     $this->assertEquals($expected, $this->queryBuilder->getGroupByParts());
 }