WC_Order::set_transaction_id PHP Method

    public function set_transaction_id($value)
    {
        $this->set_prop('transaction_id', $value);
    }

 /**
  * Test: get_transaction_id
  */
 function test_get_transaction_id()
 {
     $object = new WC_Order();
     $set_to = '12345';
     $object->set_transaction_id($set_to);
     $this->assertEquals($set_to, $object->get_transaction_id());
 }