Magento 2: join 2 table join issue

Question

When 'm trying to join two tables in Magento 2, I get an empty result. This is the initial function that returns data from single table customer_entity without any error.

\Block\Account\Message\Message.php

   public function getTestCollection()
{
    $page = ($this->getRequest()->getParam('p'))? $this->getRequest()->getParam('p') : 1;
    $pageSize = ($this->getRequest()->getParam('limit'))? $this->getRequest()->getParam('limit') : 5;

    $test = $this->_test->create();

    return $collection;
}

Later I have added following lines of codes to join first table with another custom table called affiliate_account.

    $second_table_name = $this->_resource->getTableName('affiliate_account');

    $collection->getSelect()->joinLeft(array('second' => $second_table_name), 'customer_entity.entity_id =  second.customer_id');

This returns nothing and what is the correct way to join these two tables.