In superbadge im getting this error even ive tried all the chages still it is showing "Challenge Not yet complete... here's what's wrong:
The 'MaintenanceRequest' trigger did not achieve 100% code coverage via your test methods. Make sure to 'Run All' tests in the Developer Console at least once before attempting to verify this challenge."

this is my code :
trigger MaintenanceRequest on Case (before update, after update) {
    if(Trigger.isUpdate && Trigger.isAfter){
        MaintenanceRequestHelper.updateWorkOrders(Trigger.New, Trigger.OldMap);
    }
}



public with sharing class MaintenanceRequestHelper {
    public static void updateworkOrders(List<Case> updWorkOrders, Map<Id,Case> nonUpdCaseMap) {
        Set<Id> validIds = new Set<Id>();
        For (Case c : updWorkOrders){
            if (nonUpdCaseMap.get(c.Id).Status != 'Closed' && c.Status == 'Closed'){
                if (c.Type == 'Repair' || c.Type == 'Routine Maintenance'){
                    validIds.add(c.Id);
                }
            }
        }
        
        //When an existing maintenance request of type Repair or Routine Maintenance is closed, 
        //create a new maintenance request for a future routine checkup.
        if (!validIds.isEmpty()){
            Map<Id,Case> closedCases = new Map<Id,Case>([SELECT Id, Vehicle__c, Equipment__c, Equipment__r.Maintenance_Cycle__c,
                                                          (SELECT Id,Equipment__c,Quantity__c FROM Equipment_Maintenance_Items__r) 
                                                          FROM Case WHERE Id IN :validIds]);
            Map<Id,Decimal> maintenanceCycles = new Map<ID,Decimal>();
            
            //calculate the maintenance request due dates by using the maintenance cycle defined on the related equipment records. 
            AggregateResult[] results = [SELECT Maintenance_Request__c, 
                                         MIN(Equipment__r.Maintenance_Cycle__c)cycle 
                                         FROM Equipment_Maintenance_Item__c 
                                         WHERE Maintenance_Request__c IN :ValidIds GROUP BY Maintenance_Request__c];
            
            for (AggregateResult ar : results){ 
                maintenanceCycles.put((Id) ar.get('Maintenance_Request__c'), (Decimal) ar.get('cycle'));
            }
            
            List<Case> newCases = new List<Case>();
            for(Case cc : closedCases.values()){
                Case nc = new Case (
                    ParentId = cc.Id,
                    Status = 'New',
                    Subject = 'Routine Maintenance',
                    Type = 'Routine Maintenance',
                    Vehicle__c = cc.Vehicle__c,
                    Equipment__c =cc.Equipment__c,
                    Origin = 'Web',
                    Date_Reported__c = Date.Today() 
                );
                
                //If multiple pieces of equipment are used in the maintenance request, 
                //define the due date by applying the shortest maintenance cycle to today’s date.
                //If (maintenanceCycles.containskey(cc.Id)){
                    nc.Date_Due__c = Date.today().addDays((Integer) maintenanceCycles.get(cc.Id));
                //} else {
                //    nc.Date_Due__c = Date.today().addDays((Integer) cc.Equipment__r.maintenance_Cycle__c);
                //}
                
                newCases.add(nc);
            }
            
            insert newCases;
            
            List<Equipment_Maintenance_Item__c> clonedList = new List<Equipment_Maintenance_Item__c>();
            for (Case nc : newCases){
                for (Equipment_Maintenance_Item__c clonedListItem : closedCases.get(nc.ParentId).Equipment_Maintenance_Items__r){
                    Equipment_Maintenance_Item__c item = clonedListItem.clone();
                    item.Maintenance_Request__c = nc.Id;
                    clonedList.add(item);
                }
            }
            insert clonedList;
        }
    }
}






@isTest
public with sharing class MaintenanceRequestHelperTest {
    
    // createVehicle
    private static Vehicle__c createVehicle(){
        Vehicle__c vehicle = new Vehicle__C(name = 'Testing Vehicle');
        return vehicle;
    }
    
    // createEquipment
    private static Product2 createEquipment(){
        product2 equipment = new product2(name = 'Testing equipment',
                                          lifespan_months__c = 10,
                                          maintenance_cycle__c = 10,
                                          replacement_part__c = true);
        return equipment;
    }
    
    // createMaintenanceRequest
    private static Case createMaintenanceRequest(id vehicleId, id equipmentId){
        case cse = new case(Type='Repair',
                            Status='New',
                            Origin='Web',
                            Subject='Testing subject',
                            Equipment__c=equipmentId,
                            Vehicle__c=vehicleId);
        return cse;
    }
    
    // createEquipmentMaintenanceItem
    private static Equipment_Maintenance_Item__c createEquipmentMaintenanceItem(id equipmentId,id requestId){
        Equipment_Maintenance_Item__c equipmentMaintenanceItem = new Equipment_Maintenance_Item__c(
            Equipment__c = equipmentId,
            Maintenance_Request__c = requestId);
        return equipmentMaintenanceItem;
    }
    
    @isTest
    private static void testPositive(){
        Vehicle__c vehicle = createVehicle();
        insert vehicle;
        id vehicleId = vehicle.Id;
        
        Product2 equipment = createEquipment();
        insert equipment;
        id equipmentId = equipment.Id;
        
        case createdCase = createMaintenanceRequest(vehicleId,equipmentId);
        insert createdCase;
        
        Equipment_Maintenance_Item__c equipmentMaintenanceItem = createEquipmentMaintenanceItem(equipmentId,createdCase.id);
        insert equipmentMaintenanceItem;
        
        test.startTest();
        createdCase.status = 'Closed';
        update createdCase;
        test.stopTest();
        
        Case newCase = [Select id, 
                        subject, 
                        type, 
                        Equipment__c, 
                        Date_Reported__c, 
                        Vehicle__c, 
                        Date_Due__c
                       from case
                       where status ='New'];
        
        Equipment_Maintenance_Item__c workPart = [select id
                                                  from Equipment_Maintenance_Item__c
                                                  where Maintenance_Request__c =:newCase.Id];
        list<case> allCase = [select id from case];
        system.assert(allCase.size() == 2);
        
        system.assert(newCase != null);
        system.assert(newCase.Subject != null);
        system.assertEquals(newCase.Type, 'Routine Maintenance');
        SYSTEM.assertEquals(newCase.Equipment__c, equipmentId);
        SYSTEM.assertEquals(newCase.Vehicle__c, vehicleId);
        SYSTEM.assertEquals(newCase.Date_Reported__c, system.today());
    }
    
    @isTest
    private static void testNegative(){
        Vehicle__C vehicle = createVehicle();
        insert vehicle;
        id vehicleId = vehicle.Id;
        
        product2 equipment = createEquipment();
        insert equipment;
        id equipmentId = equipment.Id;
        
        case createdCase = createMaintenanceRequest(vehicleId,equipmentId);
        insert createdCase;
        
        Equipment_Maintenance_Item__c workP = createEquipmentMaintenanceItem(equipmentId, createdCase.Id);
        insert workP;
        
        test.startTest();
        createdCase.Status = 'Working';
        update createdCase;
        test.stopTest();
        
        list<case> allCase = [select id from case];
        
        Equipment_Maintenance_Item__c equipmentMaintenanceItem = [select id 
                                                  from Equipment_Maintenance_Item__c 
                                                  where Maintenance_Request__c = :createdCase.Id];
        
        system.assert(equipmentMaintenanceItem != null);
        system.assert(allCase.size() == 1);
    }
    
    @isTest
    private static void testBulk(){
        list<Vehicle__C> vehicleList = new list<Vehicle__C>();
        list<Product2> equipmentList = new list<Product2>();
        list<Equipment_Maintenance_Item__c> equipmentMaintenanceItemList = new list<Equipment_Maintenance_Item__c>();
        list<case> caseList = new list<case>();
        list<id> oldCaseIds = new list<id>();
        
        for(integer i = 0; i < 300; i++){
            vehicleList.add(createVehicle());
            equipmentList.add(createEquipment());
        }
        insert vehicleList;
        insert equipmentList;
        
        for(integer i = 0; i < 300; i++){
            caseList.add(createMaintenanceRequest(vehicleList.get(i).id, equipmentList.get(i).id));
        }
        insert caseList;
        
        for(integer i = 0; i < 300; i++){
            equipmentMaintenanceItemList.add(createEquipmentMaintenanceItem(equipmentList.get(i).id, caseList.get(i).id));
        }
        insert equipmentMaintenanceItemList;
        
        test.startTest();
        for(case cs : caseList){
            cs.Status = 'Closed';
            oldCaseIds.add(cs.Id);
        }
        update caseList;
        test.stopTest();
        
        list<case> newCase = [select id
                                  from case
                                  where status ='New'];
        

        
        list<Equipment_Maintenance_Item__c> workParts = [select id
                                                         from Equipment_Maintenance_Item__c
                                                         where Maintenance_Request__c in: oldCaseIds];
        
        system.assert(newCase.size() == 300);
        
        list<case> allCase = [select id from case];
        system.assert(allCase.size() == 600);
    }
}