Hello,

I have completed challenge 8. I am pasting my code for classes orderTests, product2Tests,OrderHelper, Product2Extension.
Hope that helps. Please give an upvote if you are able to move forward with the challenge.
Regards,

Shubham Nandwana.
AppPerfect Corp.
salesforce@appperfect.com
408-252-4100
http://www.appperfect.com/services/salesforce/
Salesforce Development & Operations Experts

Product2Tests
@isTest (seeAllData=false)
private class Product2Tests {

    /**
     * @name product2Extension_UnitTest
     * @description UnitTest for product2Extension
    **/
  @isTest 
    static void Product2Extension_UnitTest(){
        Test.startTest();
        PageReference pageRef = Page.Product2New;
        Test.setCurrentPage(pageRef);
        Product2 prod = new Product2(name='Test',isActive=true);        
        ApexPages.StandardController stdcontroller = new ApexPages.StandardController(prod);        
        Product2Extension ext = new Product2Extension(stdcontroller);        
           System.assertEquals(Constants.DEFAULT_ROWS, ext.productsToInsert.size());
        
        ext.addRows();
        System.assertEquals(Constants.DEFAULT_ROWS * 2, ext.productsToInsert.size());
        
        for (Integer i = 0; i < 5; i++) {
            Product2Extension.ProductWrapper wrapper = ext.productsToInsert[i];
            
            Product2 testProduct = new Product2();
            testProduct.Name = 'Test Product ' + i;
            testProduct.IsActive = true;
            testProduct.Initial_Inventory__c = 20;
            testProduct.Family = Constants.PRODUCT_FAMILY[0].getValue();
            wrapper.productRecord = testProduct;
            
            PricebookEntry testEntry = new PricebookEntry();
            testEntry.IsActive = true;
            testEntry.UnitPrice = 10;
            wrapper.pricebookEntryRecord = testEntry;
        }
        
        
      
        System.debug('productTests 41'+[SELECT Id FROM CollaborationGroup WHERE Name = 'Inventory Announcements'
    ]);
        ext.save();
        
        
        ext.GetFamilyOptions();
        ext.GetInventory();
        Test.stopTest();
        List<Product2> createdProducts = [
            SELECT
                Id
            FROM
                   Product2
        ];
        System.assertEquals(5, createdProducts.size());
    }
    
    static TestMethod void Product2Trigger_UnitTest(){
        Test.startTest();
        
        Product2 p=new Product2();
        p.Name='TestProduct';
        p.Family='Side';
        p.IsActive=true;
        p.Quantity_Ordered__c =50;
        p.Initial_Inventory__c =100;
        insert p;
        CollaborationGroup c=new CollaborationGroup();
        c.Name='Test Inventory Announcements';
        c.Description='test';
       // c.OwnerId=[Select Id from Account Limit 1].Id;
        c.CollaborationType='public';
        insert c;
        
        p.Quantity_Ordered__c=96;
        update p;
            
        Test.stopTest();
    }
   

}

OrderTests
@isTest (SeeAllData=false)
private class OrderTests {
    
    @testSetup
    static void SetupTestData() {
        TestDataFactory.InsertTestData(5);
    }
 
    @isTest static void OrderExtension_UnitTest() {
        Test.startTest();
        PageReference pageRef = Page.OrderEdit;
        Test.setCurrentPage(pageRef);
        SetupTestData();
        ApexPages.StandardController stdcontroller = new ApexPages.StandardController(TestDataFactory.orders[0]);        
        OrderExtension ext = new OrderExtension(stdcontroller);        
           System.assertEquals(Constants.DEFAULT_ROWS, ext.orderItemList.size());
        ext.OnFieldChange();
        ext.SelectFamily();
        ext.Save();
        ext.First();
        ext.Next();
        ext.Previous();
        ext.Last();
        ext.GetHasPrevious();
        ext.GetHasNext();
        ext.GetTotalPages();
        ext.GetPageNumber();
        List<SelectOption> options = ext.GetFamilyOptions();
        
        Test.stopTest();
    }
    
@isTest
public static void OrderUpdate_UnitTest(){
     
   
    Test.startTest();
    SetupTestData();
    List<Order> orders = TestDataFactory.orders;
    for (Order o : orders){
        o.Status = Constants.ACTIVATED_ORDER_STATUS;
    }
    List<Product2> oldProducts = TestDataFactory.pros;
    Set<Id> productIds = new Set<Id>();
    for (Product2 oldProd : oldProducts){
        productIds.add(oldProd.Id);
    }
    oldProducts = [SELECT Id, Quantity_Ordered__c FROM Product2 WHERE ID IN :productIds];
    Map<Id, Integer> quantities = new Map<Id, Integer>();
    for (OrderItem oi : TestDataFactory.orderItems){
        Integer quantity = 0;
        List<PricebookEntry> pricebookentries = TestDataFactory.enteries;
        for (PricebookEntry pbe : pricebookentries){
            if (oi.PricebookEntryId == pbe.Id){                
                if (quantities.containsKey(pbe.Product2Id)){
                    quantity = quantities.get(pbe.Product2Id);
                }
                quantity += (Integer)oi.Quantity;
                quantities.put(pbe.Product2Id, quantity);
                break;
            }
        }
    }
   
    CollaborationGroup c=new CollaborationGroup();
        c.Name='Test Inventory Announcements';
        c.Description='test';
        //c.OwnerId=[Select Id from Account Limit 1].Id;
        c.CollaborationType='public';
        insert c;
    
    update orders;
    Map<Id, Product2> currentProducts = new Map<Id, Product2>([Select Id, Quantity_Ordered__c FROM Product2 WHERE Id IN :productIds]);
  
    for (Product2 prod : oldProducts){
      
        TestDataFactory.VerifyQuantityOrdered(prod, currentProducts.get(prod.Id), quantities.get(prod.Id));
  }
  Test.stopTest();
}
}

OrderHelper
public without sharing class OrderHelper {

    /**
     * @name AfterUpdate
     * @description 
     * @param List<Order> newList
     * @param List<Order> oldList
     * @return void
    **/
    public static List<Double> check =new List<Double>();
    public Static List<Product2> pr;
    public static void AfterUpdate(List<Order> newList, List<Order> oldList){
        
        Set<Id> orderIds = new Set<Id>();
        for ( Integer i=0; i<newList.size(); i++ ){
            if ( newList[i].Status == Constants.ACTIVATED_ORDER_STATUS && oldList[i].Status == Constants.DRAFT_ORDER_STATUS ){
                orderIds.add(newList[i].Id);
            }
        }
        
        RollUpOrderItems(orderIds);
    }

    /**
     * @name RollUpOrderItems
     * @description Given a set of Activated Order ids, query the child Order Items and related Products to calculate Inventory levels
     * @param Set<Id> activatedOrderIds
     * @return void
    **/
    public static void RollUpOrderItems(Set<Id> activatedOrderIds){
        
        //ToDo: Declare a Map named "productMap" of Ids to Product2 records
        Map<ID,Product2> productMap =new Map<ID,Product2>();
        List<OrderItem> orderId =[Select OrderID,Product2Id from OrderItem where OrderId IN: activatedOrderIds];
        
        //ToDo: Loop through a query of OrderItems related to the activatedOrderIds
        for(OrderItem o: orderId){
            //ToDo: Populate the map with the Id of the related Product2 as the key and Product2 record as the value
            Product2 p= [select name,Quantity_Ordered__c from Product2 where Id=: o.Product2Id];
            productmap.put(o.Product2Id,p );
            
        }
        //ToDo: Loop through a query that aggregates the OrderItems related to the Products in the ProductMap keyset
         pr = new List<Product2>();
        
       
        
        AggregateResult[] groupedResults =[select Product2Id ,SUM(Quantity) from OrderItem where Product2Id IN : productMap.keySet() group by Product2Id];
    
            for(AggregateResult ag: groupedResults){
                
               Product2 p= productmap.get((Id)ag.get('Product2Id'));
               p.Quantity_Ordered__c =(Double)ag.get('expr0');
               pr.add(p);
               check.add((Double)ag.get('expr0'));
               
               
            }
        
            update pr;
        
                 

        //ToDo: Perform an update on the records in the productMap
    }

}
Product2Extension
public class Product2Extension {
    //public List<Product2Extension.productWrapper> productsToInsert {get;set;}
    //public Product2Extension(ApexPages.StandardController controller){
        //productsToInsert = new List<Product2Extension.productWrapper>();          
        //AddRows();    }
    public List<ProductWrapper> productsToInsert {get;set;}
    public Product2Extension(ApexPages.StandardController controller){
        productsToInsert = new List<ProductWrapper>();
        addRows();
    }
       
    public void AddRows(){
        for ( Integer i=0; i<Constants.DEFAULT_ROWS; i++ ){
            productsToInsert.add( new Product2Extension.productWrapper() );
        }
    }
    public List<ChartHelper.ChartData> GetInventory(){
        return ChartHelper.GetInventory();
    }
    public List<SelectOption> GetFamilyOptions() {
        List<SelectOption> options = new List<SelectOption>{
            new SelectOption(Constants.SELECT_ONE, Constants.SELECT_ONE)
        };
        for (Schema.PicklistEntry ple : Constants.PRODUCT_FAMILY) {
            options.add(new SelectOption(ple.getValue(), ple.getLabel()));
        }
        return options;
    }
public PageReference Save(){
        Savepoint sp = Database.setSavepoint();
        try {
            List<Product2> products = new List<Product2>();
            List<PricebookEntry> entries = new List<PricebookEntry>();
            
            for (ProductWrapper wrp : productsToInsert){
                if(null!=wrp.productRecord && null!=wrp.pricebookEntryRecord){
                    
                    if(null!=wrp.productRecord.Name && null!=wrp.productRecord.Family && constants.SELECT_ONE!=wrp.productRecord.Family
                       && null!=wrp.productRecord.Initial_Inventory__c && null!=wrp.pricebookEntryRecord.UnitPrice){
                        products.add(wrp.productRecord);
                        PricebookEntry entry=wrp.pricebookEntryRecord;
                        entry.IsActive=true;
                        entry.Pricebook2Id=constants.STANDARD_PRICEBOOK_ID;
                        entries.add(entry);   
                    }
                }
            }
            
            insert products;            
            for (integer itr=0; itr<entries.size();itr++){
                entries[itr].Product2Id=products[itr].id;
            }
            insert entries;
            //If successful clear the list and display an informational message
            apexPages.addMessage(new ApexPages.message(ApexPages.Severity.INFO,productsToInsert.size()+' Inserted'));
            productsToInsert.clear();   //Do not remove
            addRows();  //Do not remove
        } catch (Exception e){
            Database.rollback(sp);
            apexPages.addMessage(new ApexPages.message(ApexPages.Severity.ERROR,constants.ERROR_MESSAGE));
        }
        return null;
    }        
    public class ProductWrapper{
        public product2 productRecord {get;set;}
        public pricebookEntry pricebookEntryRecord{get;set;}
        public productWrapper(){
            productRecord = new product2(Initial_Inventory__c =0);
            pricebookEntryRecord = new pricebookEntry(Unitprice=0.0);
        }
    }
}