Hi All,

I am new to Salesforce and trying to write a trigger and test class so that I can create a trigger that fires when the Active__c field on the Account object is updated to ‘No’. This trigger should find all related Case records and update their Status fields to ‘Closed’. 

This trigger should create at least 150 Accounts and at least 10 Cases for each Account. ​I need  to use assert statements to validate that my trigger is working. 

I have written the below code and getting 3 errors:

Trigger:

trigger  AccountTrigger  on  Account   ( after update )   { 
Account.CaseUpdate(Trigger.new);
}


or 


trigger  AccountTrigger  on  Account   ( after update )   { 
CaseUpdate update = new CaseUpdate();
   if (Trigger.isAfter && Trigger.isUpdate){
        update.CaseUpdate(Trigger.new);
   }   
}

=========================================================================
Class:

public class CaseUpdate {
       set <Account> accId = new Set <Id>();
       set <Cases> caseId = new Set <Id>();

  for (Case c : Trigger.new); {
  List<Case> opencase = [SELECT Id, Status, Account Id from Case where Id = :accId.Id];
 if (a.Active__c = 'No')
 {
  c.Status = 'Closed';
update opencase;
 } 
}
   }

======================================================================

Testclass:

@isTest
public   class   AccountTriggerTest  {
public   static  testMethod  void  doTest ()  {

    Account acc = new Account(
          Name = 'Test Account',

          Active__c = 'None'
       );
    insert acc;
       Case c = new Case(
           Account = acc.Id,
           Status = 'None';
       );
    insert c;
       Account accTest = [SELECT Id, Active__c FROM Account WHERE Id = :acc.id];
       System.assertEquals(accTest.Active__c, 'Yes');
       c.Status = 'Closed';
       update c;
       accTest = [SELECT Id, Active__C FROM Account WHERE Id = :acc.id];
       System.assertEquals(accTest.Status, 'Closed');
   }
}
}

Any suggestions and guidance would really help me. Thanks in advance.