Asynchronous Apex "Using Future Methods"

Create an Apex class that uses the @future annotation to update Account records.

Create an Apex class with a method using the @future annotation that accepts a List of Account IDs and updates a custom field on the Account object with the number of contacts associated to the Account. Write unit tests that achieve 100% code coverage for the class.

• Create a field on the Account object called 'Number_of_Contacts__c' of type Number. This field will hold the total number of Contacts for the Account.
• Create an Apex class called 'AccountProcessor' that contains a 'countContacts' method that accepts a List of Account IDs. This method must use the @future annotation.
• For each Account ID passed to the method, count the number of Contact records associated to it and update the 'Number_of_Contacts__c' field with this value.
• Create an Apex test class called 'AccountProcessorTest'.
• The unit tests must cover all lines of code included in the AccountProcessor class, resulting in 100% code coverage.
• Run your test class at least once (via 'Run All' tests the Developer Console) before attempting to verify this challenge.

AccountProcessor class:

public class AccountProcessor {

    @future

    public static void countContacts(List<ID> accIds){

        List<Account> listacc = [SELECT id,Number_of_Contacts__c,(SELECT id from contacts) from account where id in : accIds];

        for (account acc : listacc){

            List<Contact> con = acc.contacts;

            acc.Number_of_Contacts__c = con.size();

        }

        update listacc;

    }

}

AccountProcessTest class:

@isTest

public class AccountProcessorTest {

    public static testmethod void TestAccountProcessorTest(){

     Account a = new Account();

        a.Name = 'Test Account';

        Insert a;

        system.debug('account a :'+a.id);

        

        Contact cont = New Contact();

        cont.FirstName ='Ankit';

        cont.LastName ='Avula';

        cont.AccountId = a.Id;

        Insert cont;

        system.debug('contact cont :' +cont.id);

        

        List<Id> accIds = new List<Id>();

        accIds.add(a.Id);

        

        Test.startTest();

        AccountProcessor.countContacts(accIds);

        Test.stopTest();

        

        Account ACC = [select Number_of_Contacts__c from Account where id = :a.id LIMIT 1];

        System.assertEquals(ACC.Number_of_Contacts__c, 1);

    }

}