This is My snippet Which i need to cover in My test class .
class  :-
Public class UpdateTerritorySectionFields{
Public static Void  ofOnsiteatPSCUInProgressUp(List<Territory_Plan__c> tpe){
           Set<Id> ownerIds =New set<Id>();
           List<Event> evtList = new List<Event>();
           List<Territory_Plan__c > ObjectRec = new List<Territory_Plan__c >(); 
           List<Territory_Plan__c> tpList = new List<Territory_Plan__c>();
           List<Territory_Plan__c > ObjectBList = new List<Territory_Plan__c >();
           List<Opportunity> oppoList = new List<Opportunity>();           
           for(Territory_Plan__c t:tpe){
               ownerIds.add(t.Account_Executive__c);
            }
            Map<Id, Opportunity> oppoMap = new Map<Id, Opportunity>([SELECT Id, StageName, ownerId FROM Opportunity WHERE OwnerId IN : ownerIds]);
            evtList = [SELECT Id, WhatId, Status__c, Type, ownerId FROM Event WHERE Status__c='Scheduled' AND Type='On-Site at PSCU' AND ownerID IN:ownerIds];
            for(Territory_Plan__c tp:tpe){
               for(Event e: evtList){
                    if(tp.Account_Executive__c==e.ownerId && oppoMap.containsKey(e.WhatId) && tp.Account_Executive__c==oppoMap.get(e.WhatId).ownerId){
                       oppoList.add(oppoMap.get(e.WhatId));
                    }
                }    
tp.of_Onsite_at_PSCU_In_Progress__c = oppoList.size();
                tpList.add(tp);
            }
            update tpList;
            }
}

Test class :-
@isTest
public class testUpTerritorySectionFields {
Public Static testMethod Void UpdateTerFromEvent(){
         User u = getUserRecord();
        territory_Plan__c tp = new territory_Plan__c(Account_Executive__c=u.id);
        insert tp;
        
          
        Opportunity opp = new Opportunity(Name='Chicago Patrolmens FCU AFA',PSCU_Opp_Referred_By__c=u.id,StageName='06 - Sale Closed',CloseDate=Date.Today(),Probability=100,PSCU_Contract_Term__c='2',ownerid=u.id );
        Insert opp;
        List<Event> ev =new List<Event>();
        Event e1 =new Event(Type='On-Site at PSCU',Status__c='Scheduled',OwnerId=u.id,WhatId =opp.Id,DurationInMinutes=5,ActivityDateTime=Date.TOday()+2);
            ev.add(e1);
        Event e2 =new Event(Type='On-Site at PSCU',Status__c='Completed',OwnerId=u.id,WhatId =opp.Id,DurationInMinutes=5,ActivityDateTime=Date.TOday()+2,AddressType__c='Mailing Address');
        ev.add(e2);
        Event e3 =new Event(Type='On-Site at Account',Status__c='Scheduled',OwnerId=u.id,WhatId =opp.Id,DurationInMinutes=5,ActivityDateTime=Date.TOday()+2,AddressType__c='Mailing Address');
        ev.add(e3);
        Event e4 =new Event(Type='On-Site at Account',Status__c='Completed',OwnerId=u.id,WhatId =opp.Id,DurationInMinutes=5,ActivityDateTime=Date.TOday()+2,AddressType__c='Mailing Address');
        ev.add(e4);
        Event e5 =new Event(Type='Call/Webinar with CU',Status__c='Completed',OwnerId=u.id,WhatId =opp.Id,DurationInMinutes=5,ActivityDateTime=Date.TOday()+2,AddressType__c='Mailing Address');
        ev.add(e5);
        Event e6 =new Event(Type='Call/Webinar with CU',Status__c='Scheduled',OwnerId=u.id ,WhatId =opp.Id,DurationInMinutes=5,ActivityDateTime=Date.TOday()+2,AddressType__c='Mailing Address');
        ev.add(e6);
        Insert ev;
        
        List<Event> Evnt = [select Type,Status__c,OwnerId,DurationInMinutes,ActivityDateTime from Event Where WhatId=:opp.Id LIMIT 6 ];
        Update Evnt;
        
        
    } 
}