Test Class :-

@IsTest
public class OpportunityHandlerTest 
{
   //public static String VAR_EXP = '0 0 0 15 3 ? 2022'; 
   
   private static testmethod void MyUnitTest()
   {  
       Integer MAX_QUERY = Limits.getLimitQueries();
       Integer NUM_QUERY = MAX_QUERY - 1; 
      //Create accunt
      Account acc = new account();
      acc.name='test';
      try
      {
          insert acc;
          system.debug('this is acc' +acc); 
      }
      catch(DMLException de)
      {
           system.debug('a is failed' +de.getMessage());
      }
      
       //Create contact 1
       Contact c=new Contact();
       c.lastname='nunes';
       c.Accountid=acc.id;
       c.LeadSource='Inbound';
       c.Contact_Status__c='Open';
       c.New_Lead_Source__c='Inbound';
       c.Pre_Demo_Notes__c='from pre contact';
       c.Post_Demo_Notes__c='from post contact';
       c.Created_in_admin_panel__c=true;
       insert c;
       system.assert(c.id != null);
       
       //Create contact 2
       Contact c2=new Contact();
       c2.lastname='nunes';
       c2.Accountid=acc.id;
       c2.LeadSource='Inbound';
       c2.Contact_Status__c='Open';
       c2.New_Lead_Source__c='Inbound';
       c2.Pre_Demo_Notes__c='from pre contact';
       c2.Post_Demo_Notes__c='from post contact';
       c2.Created_in_admin_panel__c=true;
       insert c2;
       system.assert(c2.id != null);
       
       
        Opportunity opp1 = new Opportunity(AccountId=acc.id,Upsell_Potential__c='No', Name='o2',contact_name__c=c.id, CloseDate=System.today(), StageName='Prospecting',Product_Specialist__c='Nicolas Carreras');
        insert opp1;

        Opportunity opp=[Select id,Contact_Name__c from Opportunity where contact_name__c != null ];
        opp.name='Start';
        opp.Contact_Name__c=c2.id;
        update opp;

        Opportunity opp2 = new Opportunity(AccountId=acc.id,Upsell_Potential__c='No', Name='o2', CloseDate=System.today(), StageName='Prospecting',Product_Specialist__c='Nicolas Carreras');
        insert opp2;

        Opportunity opp3 = new Opportunity
        (AccountId=acc.id,
        Upsell_Potential__c='SDR Target', 
        Name='o3', 
        CloseDate=System.today(), 
        StageName='Closed Won',
        Product_Specialist__c='Nicolas Carreras',
        Catalyst__c='Greenfield'
        //RenewalDate__c=system.today()
        );
        insert opp3;
        
        opp3.StageName = 'Prospecting';
        update opp3;
        
        opp3.StageName = 'Closed Won';
        update opp3; 
        
         OpportunityContactRole opcr=new OpportunityContactRole();
         opcr.OpportunityId = opp3.id;
         opcr.ContactId = c2.id;
         opcr.IsPrimary = true;
         opcr.Role='End-User';
         insert opcr;
        system.assert(opcr.id != null); 
        
        Id stdpricebook = System.Test.getStandardPricebookId();
        system.debug('this is stdpricebook : ' +stdpricebook);
        system.assert(stdpricebook != null);
        
        List<SBQQ__Quote__c> qlist=new List<SBQQ__Quote__c>();
        SBQQ__Quote__c thisquote=new SBQQ__Quote__c();
        thisquote.SBQQ__SubscriptionTerm__c=12;
        thisquote.SBQQ__StartDate__c=system.today();
        thisquote.SBQQ__PriceBook__c=stdpricebook;
        thisquote.SBQQ__Primary__c=true;
        thisquote.SBQQ__Opportunity2__c=opp3.id;
        qlist.add(thisquote);
        //try{
        Test.startTest();
        insert qlist;
        Test.stopTest();
        //}
        ////catch(exception e)
        //{
        //system.debug(e);
        //}
        System.assert(thisquote.id != null);
        
        set<id> setid = new set<id>();
        
        for(SBQQ__Quote__c a : qlist){
        
        setid.add(a.id);
        }
        
       // list<SBQQ__Quote__c> insrtdQ = 
        list<SBQQ__QuoteLine__c> qq = [select id from SBQQ__QuoteLine__c where id=:setid];
        List<SBQQ__QuoteLine__c> newQlils = new List<SBQQ__QuoteLine__c>();   
          
       for(SBQQ__QuoteLine__c qq1 :qq ){
       
       if(qq1.id != null){
       SBQQ__QuoteLine__c QL = new SBQQ__QuoteLine__c();
     //  QL.SBQQ__Quote__c = setid;
       
       }
       }
       
     }  
                 
}

Apex Class:-

public class OpportunityHandler_cpq{

public integer enddate;

    Public void CpqQuoteInsert( list<opportunity> listopp){
        
        set<id> oppids = new set<id>();
      
        for(opportunity op :listopp ) {
      
            if(op.SBQQ__Renewal__c == True &&  op.SBQQ__RenewedContract__c != null ){

              oppids.add(op.id);
              system.debug('First op id'+op.id);
            }
        }
        system.debug('oppids::'+oppids);  
        List<Opportunity> oppls = [select id,Renewal_Contract_Term__c,SBQQ__RenewedContract__c, formulapreviousopp__c, SBQQ__RenewedContract__r.SBQQ__Opportunity__c from opportunity where id IN : oppids];
        system.debug('oppls::'+oppls);  
        Map<Id, Id> oldVSnewOpp = new Map<Id, Id>();
   
        for(Opportunity opp: oppls) {
            system.debug('opp.SBQQ__RenewedContract__c::'+opp.SBQQ__RenewedContract__c);
            system.debug('opp.SBQQ__RenewedContract__r.SBQQ__Opportunity__c::'+opp.SBQQ__RenewedContract__r.SBQQ__Opportunity__c);
            system.debug('opp.formulapreviousopp__::'+opp.formulapreviousopp__c);
            
            if(opp.SBQQ__RenewedContract__c != null && opp.SBQQ__RenewedContract__r.SBQQ__Opportunity__c != null)
                oldVSnewOpp.put(opp.SBQQ__RenewedContract__r.SBQQ__Opportunity__c, opp.Id);
     
        }
        system.debug('oldVSnewOpp:'+oldVSnewOpp);
        List<Opportunity> oldOppls = [select id, name,
                                                (Select ACV_Auto_Renew_Increment_Amount__c, ACV__c, Account_Name__c, Auto_Renew__c, Contract_End_Date__c, CreatedById, CreatedDate, Document_Template__c, 
Id, IsDeleted, LastActivityDate, LastModifiedById, LastModifiedDate, LastReferencedDate, LastViewedDate, Name, Number_of_Licences__c, 
Opp_Closed__c, Original_Quote_id__c, OwnerId, Payment__c, Primary_Contact_First_Name__c, Product_Family__c, SBQQ__Account__c, 
SBQQ__AdditionalDiscountAmount__c, SBQQ__AverageCustomerDiscount__c, SBQQ__AveragePartnerDiscount__c, SBQQ__BillingCity__c, SBQQ__BillingCountry__c, 
SBQQ__BillingFrequency__c, SBQQ__BillingName__c, SBQQ__BillingPostalCode__c, SBQQ__BillingState__c, SBQQ__BillingStreet__c, SBQQ__ContractingMethod__c,
 SBQQ__CustomerAmount__c, SBQQ__CustomerDiscount__c, SBQQ__DaysQuoteOpen__c, SBQQ__DefaultTemplate__c, SBQQ__DeliveryMethod__c, SBQQ__DistributorDiscount__c,
 SBQQ__Distributor__c, SBQQ__DocumentStatus__c, SBQQ__EmailTemplateId__c, SBQQ__EndDate__c, SBQQ__ExpirationDate__c, SBQQ__FirstSegmentTermEndDate__c,
 SBQQ__GenerateContractedPrice__c, SBQQ__Introduction__c, SBQQ__Key__c, SBQQ__LineItemCount__c, SBQQ__LineItemsGrouped__c, SBQQ__LineItemsPrinted__c, 
 SBQQ__ListAmount__c, SBQQ__MarkupRate__c, SBQQ__MasterContract__c, SBQQ__NetAmount__c, SBQQ__Notes__c, SBQQ__Opportunity2__c, SBQQ__Ordered__c, 
 SBQQ__OriginalQuote__c, SBQQ__PartnerDiscount__c, SBQQ__Partner__c, SBQQ__PaymentTerms__c, SBQQ__PriceBook__c, SBQQ__PricebookId__c,
 SBQQ__PrimaryContact__c, SBQQ__Primary__c, SBQQ__QuoteProcessId__c, SBQQ__QuoteTemplateId__c, SBQQ__RegularAmount__c, SBQQ__SalesRep__c, 
 SBQQ__ShippingCity__c, SBQQ__ShippingCountry__c, SBQQ__ShippingName__c, SBQQ__ShippingPostalCode__c, SBQQ__ShippingState__c, SBQQ__ShippingStreet__c, 
 SBQQ__Source__c, SBQQ__StartDate__c, SBQQ__Status__c, SBQQ__SubscriptionTerm__c, SBQQ__TargetCustomerAmount__c, SBQQ__TotalCustomerDiscountAmount__c,
 SBQQ__Type__c, SBQQ__WatermarkShown__c, SystemModstamp
                                                from SBQQ__Quotes2__r where SBQQ__Primary__c =  true) 
                                    from opportunity where id IN :oldVSnewOpp.keySet()];
         system.debug('oldOppls:'+oldOppls);
     
        List<SBQQ__Quote__c>  quotels = new  List<SBQQ__Quote__c>();
        for(Opportunity oldOpp :oldOppls) {
            if(oldOpp.SBQQ__Quotes2__r.size() >0 ) {
                system.debug('oldOpp.SBQQ__Quotes2__r::'+oldOpp.SBQQ__Quotes2__r);
                system.debug('oldVSnewOpp.containsKey(oldOpp.id)::'+oldVSnewOpp.containsKey(oldOpp.id));
                if(oldVSnewOpp.containsKey(oldOpp.id)) {
                    system.debug('here!!!!!!');
                    SBQQ__Quote__c  quote1 =  oldOpp.SBQQ__Quotes2__r[0].clone();
                    quote1.Original_Quote_id__c=oldOpp.SBQQ__Quotes2__r[0].id;
                    quote1.SBQQ__StartDate__c = system.today();
                    
                 //  Integer enddate= Integer.valueOf(String.valueOf(Math.roundToLong(oldOpp.SBQQ__Quotes2__r[0].SBQQ__SubscriptionTerm__c)));
                    
              //   quote1.SBQQ__EndDate__c =system.today().addmonths(enddate);

                    system.debug('quote1.Original_Quote_id__c::'+quote1.Original_Quote_id__c);
                    quote1.SBQQ__Opportunity2__c = oldVSnewOpp.get(oldOpp.id);
                    system.debug('quote1::'+quote1);
                    quotels.add(quote1);
                } 
         
            }
     
        }
        system.debug('quotels::'+quotels);
        
        if(quotels.size()>0) {
            insert quotels;
        }
        
       
        
         set<id> Quoteid = new set<id>();
         Map<id, id> oldQuoteVSNewQuoteIds = new Map<id, id>();
         for(SBQQ__Quote__c qt : quotels){
            if(qt.Original_Quote_id__c != null){
                oldQuoteVSNewQuoteIds.put(qt.Original_Quote_id__c, qt.id);
            }
        }
        system.debug('oldQuoteVSNewQuoteIds:::'+oldQuoteVSNewQuoteIds);
        
        list<SBQQ__Quote__c> oldquotelist = [Select ACV_Auto_Renew_Increment_Amount__c, ACV__c, Account_Name__c, Auto_Renew__c, Contract_End_Date__c, CreatedById, CreatedDate, Document_Template__c, 
Id, IsDeleted, LastActivityDate, LastModifiedById, LastModifiedDate, LastReferencedDate, LastViewedDate, Name, Number_of_Licences__c, 
Opp_Closed__c, Original_Quote_id__c, OwnerId, Payment__c, Primary_Contact_First_Name__c, Product_Family__c, SBQQ__Account__c, 
SBQQ__AdditionalDiscountAmount__c, SBQQ__AverageCustomerDiscount__c, SBQQ__AveragePartnerDiscount__c, SBQQ__BillingCity__c, SBQQ__BillingCountry__c, 
tartDate__c, SBQQ__Status__c, SBQQ__SubscriptionTerm__c, SBQQ__TargetCustomerAmount__c, SBQQ__TotalCustomerDiscountAmount__c,
 SBQQ__Type__c, SBQQ__WatermarkShown__c, SystemModstamp,
                                              (Select CreatedById, CreatedDate, Id, IsDeleted, LastModifiedById, LastModifiedDate, Name, Opportunity__c, Product_Description__c, Product_Family__c, 
SBQQ__AdditionalDiscountAmount__c, SBQQ__AdditionalDiscount__c, SBQQ__AdditionalQuantity__c, SBQQ__AllowAssetRefund__c, SBQQ__BatchQuantity__c, 
SBQQ__BillingFrequency__c, SBQQ__BillingType__c, SBQQ__BlockPrice__c, SBQQ__Bundle__c, SBQQ__BundledQuantity__c, SBQQ__Bundled__c, SBQQ__CarryoverLine__c,
 SBQQ__ChargeType__c, SBQQ__ComponentCost__c, SBQQ__ComponentDiscountedByPackage__c, SBQQ__ComponentListTotal__c, SBQQ__ComponentSubscriptionScope__c, 
 
 
 SBQQ__TotalDiscountRate__c, SBQQ__UnitCost__c, SBQQ__UnproratedNetPrice__c, SBQQ__UpgradedAsset__c, SBQQ__UpgradedQuantity__c, 
 SBQQ__UpgradedSubscription__c, SBQQ__UpliftAmount__c, SBQQ__Uplift__c, SBQQ__VolumeDiscount__c, SystemModstamp  FROM SBQQ__Lineitems__r) FROM SBQQ__Quote__c 
                                                   where id IN :oldQuoteVSNewQuoteIds.keySet()];
                                              
        List<SBQQ__QuoteLine__c> newQlils = new List<SBQQ__QuoteLine__c>();                                           
        for(SBQQ__Quote__c q1 :oldquotelist){
            for(SBQQ__QuoteLine__c qli : q1.SBQQ__Lineitems__r){
                SBQQ__QuoteLine__c newQli = qli.clone();
                newQli.SBQQ__Quote__c = oldQuoteVSNewQuoteIds.get(q1.id);
                newQli.SBQQ__Product__c= qli.SBQQ__Product__c;
                
                system.debug('qli:::'+qli.SBQQ__ProductFamily__c+ '::'+qli);
                system.debug('newQli:::'+newQli.SBQQ__ProductFamily__c+ '::'+newQli);

                newQlils.add(newQli);  
            } 
        }
        
        system.debug('newQlils::'+newQlils.size() + '::' +newQlils);
        if(newQlils.size() > 0) {
            insert newQlils;
        
        }
      /*  set<Id> newIds = new Set<Id>();
        for(SBQQ__QuoteLine__c qliNew1 :newQlils) {
            newIds.add(qliNew1.id);
        }
        
    
    List<SBQQ__QuoteLine__c>  updatedValue = [select id, name, SBQQ__CustomerPrice__c,SBQQ__ProductFamily__c  from SBQQ__QuoteLine__c where id IN :newIds];                                      
    system.debug('updatedValue::'+updatedValue);
    for(SBQQ__QuoteLine__c a1  :updatedValue) {
        system.debug('a1::'+a1);
    
    }
        */
        
        set<id> newQuoteid = new set<id>();
       
       for(SBQQ__Quote__c qt2 :quotels){
       newQuoteid.add(qt2.id);
       
       }
       
     //  list<string> updateTerm = new list<string>();
        
        list<SBQQ__Quote__c> newQuote =[select SBQQ__SubscriptionTerm__c, Renewal_Contract_Term_from_Renewal_opp__c, SBQQ__EndDate__c from  SBQQ__Quote__c where id=:newQuoteid];

        for(SBQQ__Quote__c updateEnddate: newQuote){
        
           Integer enddate= Integer.valueOf(String.valueOf(Math.roundToLong(updateEnddate.Renewal_Contract_Term_from_Renewal_opp__c)));

        
        updateEnddate.SBQQ__EndDate__c = system.today().addMonths(enddate);
        
        updateEnddate.SBQQ__SubscriptionTerm__c =updateEnddate.Renewal_Contract_Term_from_Renewal_opp__c;
        
        update updateEnddate;
        }

    } 
        
}