public function testAddSelect()
 {
     $qb = new QueryBuilder($this->qf);
     $this->assertCount(0, $qb->getColumns());
     $qb->addSelect('selectorName', 'propertyName', 'columnName');
     $this->assertCount(1, $qb->getColumns());
     $qb->addSelect('selectorName', 'propertyName', 'columnName');
     $this->assertCount(2, $qb->getColumns());
 }