public function testReduce() { $resultSet = new ResultSet(array(1 => array('_id' => 1, 'field' => '10'), 2 => array('_id' => 2, 'field' => '20'), 3 => array('_id' => 3, 'field' => '30'))); $value = $resultSet->reduce(function ($accumulator, $item) { $accumulator += $item['field']; return $accumulator; }, 0); $this->assertEquals(60, $value); }