Elastica\Cluster\Health::getNumberOfDataNodes PHP Method

    public function getNumberOfDataNodes()
    {
        return $this->_data['number_of_data_nodes'];
    }

 /**
  * @group unit
  */
 public function testGetNumberOfDataNodes()
 {
     $this->assertEquals(8, $this->_health->getNumberOfDataNodes());
 }