Elastica\Search::addIndex PHP Method

    public function addIndex($index)
    {
        if ($index instanceof Index) {
            $index = $index->getName();
        }
        if (!is_scalar($index)) {
            throw new InvalidException('Invalid param type');
        }
        $this->_indices[] = (string) $index;
        return $this;
    }

 /**
  * @group functional
  */
 public function testShouldReturnTheRightNumberOfResult()
 {
     $filter = new Nested();
     $this->assertEquals(array('nested' => array()), $filter->toArray());
     $query = new Terms();
     $query->setTerms('hobby', array('guitar'));
     $filter->setPath('hobbies');
     $filter->setFilter($query);
     $client = $this->_getClient();
     $search = new Search($client);
     $index = $this->_getIndexForTest();
     $search->addIndex($index);
     $resultSet = $search->search($filter);
     $this->assertEquals(1, $resultSet->getTotalHits());
     $filter = new Nested();
     $this->assertEquals(array('nested' => array()), $filter->toArray());
     $query = new Terms();
     $query->setTerms('hobby', array('opensource'));
     $filter->setPath('hobbies');
     $filter->setFilter($query);
     $client = $this->_getClient();
     $search = new Search($client);
     $index = $this->_getIndexForTest();
     $search->addIndex($index);
     $resultSet = $search->search($filter);
     $this->assertEquals(2, $resultSet->getTotalHits());
 }