Hi All,

This is my trigger

trigger ETicketAirlineUrlTrigger on E_Ticket__c (after insert, after update) {
 
    List<E_Ticket__c> listEt = new List<E_Ticket__c>();
      for(E_Ticket__c et : Trigger.New)
      {
          E_Ticket__c etNew = [SELECT Id,Airline__c FROM E_Ticket__c WHERE Id =:et.id];
          if(etNew.Airline__c =='Virgin Australia')
          {    
            etNew.Airlines_Url__c = '<a href="http://www.virginaustralia.com/Personal/Bookings/Managebookings/index.htm">Virgin Australia</a>';
          }
          else if(etNew.Airline__c =='Virgin Atlantic')
          {
            etNew.Airlines_Url__c = '<a href="https://www.virgin-atlantic.com/en/us/manageyourflights/updatebooking/index.jsp">Virgin Atlantic</a>';
          }
          listEt.add(etNew);
      }
      if(listEt.size()>0)
      update listEt;
}

And test case is

@isTest
private class ETicketAirlineUrlTestCase {

    static testMethod void myUnitTest() {
        Opportunity oppNew =  new Opportunity();
        oppNew.Name = 'Test Opp';
        oppNew.StageName = 'To Be Searched';
        oppNew.CloseDate = System.now().date();
        insert oppNew;
        
        E_Ticket__c et =  new E_Ticket__c();
        et.Airline__c = 'Virgin Australia';
        et.Opportunity__c = oppNew.Id;
        insert et;
        
        List<E_Ticket__c> listEt = new List<E_Ticket__c>();
        
        E_Ticket__c etOld = [SELECT Id,Airline__c FROM E_Ticket__c WHERE Id =:et.Id];
        etOld.Airline__c = 'Virgin Atlantic';
        listEt.add(etOld);
        if (listEt != null && !listEt.isEmpty())
          {
             Database.update(listEt);
          }
    }
}

Getting following error

System.DmlException: Insert failed. First exception on row 0; first error: CANNOT_INSERT_UPDATE_ACTIVATE_ENTITY, ETicketAirlineUrlTrigger: execution of AfterInsert

What is wrong here?

Thanks