Hello,

thanks for your explanation.

Unfortunately, th trigger is not working. Here is the updated trigger:

trigger insertNewOpportunity on Opportunity (after insert, after update) {
List<Opportunity> listOppor = new List<Opportunity>();
for(Opportunity opp : Trigger.new)
{
   
     if(opp.StageName == 'Closed Won' && opp.Account != null && opp.N_Of_Hotels_Payed__c < opp.Account.N_of_Hotels__c)
       {
          Opportunity oppNew = opp.clone(true);
          oppNew.Type = 'Upsell';
          //By chaning status you will by pass trigger for newly created opportunity
          //Some StageName except the one used in entry condition (Closed Won in your case)
          oppNew.StageName = 'Contract Sent';
          listOppor.add(oppNew);
       }
    if(listOppor.size() > 0)
     insert listOppor;    
   
}
}

 And this is the Test:

/**
 * This class tests the trigger named AddCampaign.
 */
@isTest
private class UpsellOppTest {

    static testMethod void UpsellOppTest() {       
                    
        //Data Prep
        
        //Create Account, Opportunity, Product, etc.
        Account acct1 = new Account(name='test Account One1');
        acct1.Type = 'Chain';
        acct1.N_of_Hotels__c = 10;
        insert acct1;
        
        //Create Opportunity on Account
        Opportunity Oppty1 = new Opportunity(name='test Oppty One1');
        Oppty1.AccountId = acct1.Id;
        Oppty1.StageName = 'Closed Won';
        Oppty1.CloseDate = Date.today();
        
        insert Oppty1;   
        
         //Create Opportunity on Account
        Opportunity Oppty2 = new Opportunity(name='test Oppty One2');
        Oppty2.AccountId = acct1.Id;
        Oppty2.StageName = 'Contract Sent';
        Oppty2.CloseDate = Date.today();
        
       
        insert Oppty2;              
                        
       // Create Products 
         Product2 testprod1 = new Product2 (name='TRIAL');
         testprod1.productcode = 'TRL';
         insert testprod1;
         
         Product2 testprod2 = new Product2 (name='ADVANCED');
         testprod2.productcode = 'ADV';
         insert testprod2;

// Ger Pricebook
         Pricebook2 testpb = [select id from Pricebook2 where IsStandard = true];   

// Add to pricebook
         PricebookEntry testpbe1 = new PricebookEntry ();
         testpbe1.pricebook2id = testpb.id;
         testpbe1.product2id = testprod1.id;
         testpbe1.IsActive = True;
         testpbe1.UnitPrice = 250;
         testpbe1.UseStandardPrice = false;
         insert testpbe1;
         PricebookEntry testpbe2 = new PricebookEntry ();
         testpbe2.pricebook2id = testpb.id;
         testpbe2.product2id = testprod2.id;
         testpbe2.IsActive = True;
         testpbe2.UnitPrice = 250;
         testpbe2.UseStandardPrice = false;
         insert testpbe2;
         
         
                //And now you want execute the startTest method to set the context 
                //of the following apex methods as separate from the previous data 
                //preparation or DML statements.  
        test.starttest();
        
          // add the line item which should call the trigger
          // with this line item it should fail out quickly 
          // As Auto Schedule is false
    OpportunityLineItem oli1 = new OpportunityLineItem();
    oli1.Quantity = 1;
    oli1.Months__c = 12;
    oli1.TotalPrice = 1;
    oli1.PricebookEntryId = testpbe1.id;
    oli1.OpportunityId = oppty1.id;    
    insert oli1;   
    
            
          // add the line item which should call the trigger
          // Auto Schedule is true so it should build the schedule.
    OpportunityLineItem oli2 = new OpportunityLineItem();
    oli2.Quantity = 2;
    oli2.Months__c = 12;
    oli2.TotalPrice = 1;
    oli2.PricebookEntryId = testpbe2.id;
    oli2.OpportunityId = oppty1.id;    
    insert oli2;
     
         
    
           
        test.stoptest();
    }
}

Test is covering only 44% and Trigger is not inserting and Opportunity.

What's wrong according to you?

Many thanks in advance.

Stefano