public function testOperations()
 {
     $op = new FilterOperation('id', '<=', 3);
     $this->operations->add($op);
     self::assertEquals(3, $this->service->count(), 'Test filtering');
     $this->operations->remove($op);
     self::assertEquals($this->totalCount, $this->service->count(), 'Test recalc. after removing operation');
 }