Salesforce How You need to update a related child record whenever a parent record’s status changes, but only if the status is “Closed Won.” How would you design this in Apex?

// Trigger
trigger OpportunityTrigger on Opportunity (after update) {
    OpportunityTriggerHandler.handleAfterUpdate(Trigger.new, Trigger.oldMap);
}

public class OpportunityTriggerHandler {
    
    public static void handleAfterUpdate(List<Opportunity> newOpps, Map<Id, Opportunity> oldMap) {
        Set<Id> closedWonOppIds = new Set<Id>();
        
        // Collect only opportunities that changed to Closed Won
        for (Opportunity opp : newOpps) {
            Opportunity oldOpp = oldMap.get(opp.Id);
            
            if (opp.StageName == 'Closed Won' && 
                opp.StageName != oldOpp.StageName) {
                closedWonOppIds.add(opp.Id);
            }
        }
        
        if (!closedWonOppIds.isEmpty()) {
            updateRelatedOpportunityLineItems(closedWonOppIds);
        }
    }
    
    private static void updateRelatedOpportunityLineItems(Set<Id> oppIds) {
        List<OpportunityLineItem> lineItemsToUpdate = new List<OpportunityLineItem>();
        
        // Query child records
        for (OpportunityLineItem oli : [
            SELECT Id, Status__c, OpportunityId
            FROM OpportunityLineItem
            WHERE OpportunityId IN :oppIds
        ]) {
            oli.Status__c = 'Active';
            oli.Last_Updated_Date__c = System.today();
            lineItemsToUpdate.add(oli);
        }
        
        // Bulk update with error handling
        if (!lineItemsToUpdate.isEmpty()) {
            try {
                update lineItemsToUpdate;
            } catch (DmlException e) {
                System.debug('Error updating line items: ' + e.getMessage());
                // Add error to parent record if needed
                for (Integer i = 0; i < e.getNumDml(); i++) {
                    System.debug('Failed record: ' + e.getDmlId(i));
                }
            }
        }
    }
}

// Collect IDs in a Set for bulk processing
Set<Id> closedWonOppIds = new Set<Id>();

public class OpportunityTriggerHandler {
    
    @TestVisible private static Boolean bypassTrigger = false;
    
    public static void handleAfterUpdate(List<Opportunity> newOpps, Map<Id, Opportunity> oldMap) {
        // Check bypass
        if (bypassTrigger || TriggerBypassManager.isBypassed('Opportunity')) {
            return;
        }
        
        // Rest of logic...
    }
}

@isTest
private class OpportunityTriggerHandlerTest {
    
    @testSetup
    static void setup() {
        // Create test data
        Opportunity opp = new Opportunity(
            Name = 'Test Opp',
            StageName = 'Prospecting',
            CloseDate = System.today().addDays(30)
        );
        insert opp;
        
        OpportunityLineItem oli = new OpportunityLineItem(
            OpportunityId = opp.Id,
            PricebookEntryId = /* your price book entry */,
            Quantity = 1,
            UnitPrice = 100,
            Status__c = 'Pending'
        );
        insert oli;
    }
    
    @isTest
    static void testClosedWonUpdatesChildren() {
        Opportunity opp = [SELECT Id, StageName FROM Opportunity LIMIT 1];
        
        Test.startTest();
        opp.StageName = 'Closed Won';
        update opp;
        Test.stopTest();
        
        OpportunityLineItem oli = [SELECT Status__c FROM OpportunityLineItem LIMIT 1];
        System.assertEquals('Active', oli.Status__c, 'Child record should be updated');
    }
    
    @isTest
    static void testBulkUpdate() {
        // Test with 200 opportunities
        List<Opportunity> opps = [SELECT Id FROM Opportunity];
        
        Test.startTest();
        for (Opportunity opp : opps) {
            opp.StageName = 'Closed Won';
        }
        update opps;
        Test.stopTest();
        
        // Assert all children updated
    }
}

private static void updateRelatedOpportunityLineItems(Set<Id> oppIds) {
    if (!System.isBatch() && !System.isFuture()) {
        updateChildRecordsAsync(oppIds);
    }
}

@future
private static void updateChildRecordsAsync(Set<Id> oppIds) {
    // Same update logic
}