global class LeadProcessor implements Database.Batchable<sObject>{

    global integer recordsProcessed = 1;
    
    global Database.QueryLocator start(Database.BatchableContext bc){
       return Database.getQueryLocator('SELECT ID, LeadSource from Lead where LeadSource = \'Dreamforce\'');
    }
        
    
    global void execute(Database.BatchableContext bc, List<Lead> scope){
        for(Lead l : scope){
      
            l.LeadSource = 'Web';
        }
        update scope;        
    }
          
	global void finish(Database.BatchableContext bc){
     System.debug(recordsProcessed + ' records processed. Shazam!');
        AsyncApexJob job = [SELECT Id, Status, NumberOfErrors, 
            JobItemsProcessed,
            TotalJobItems, CreatedBy.Email
            FROM AsyncApexJob
            WHERE Id = :bc.getJobId()];
        // call some utility to send email
       // EmailUtils.sendMessage(a, recordsProcessed);
    }     
}

@isTest
public class LeadProcessorTest {
	
     @testSetup
     static void setupLeads() {
        List<Lead> leads = new List<Lead>();
        // insert 200 accounts
        for (Integer i=0;i<200;i++) {
            leads.add(new Lead(company = 'testCompany' + i, 
                Leadsource='DreamForce', LastName = 'LeadingEdge' + i));
        }
        insert leads;
}
    
    @isTest
    static void testUpdateLeadBatch(){
        List<lead> leadsForUpdate =[select id, LeadSource from Lead where LeadSource = 'Dreamforce'];
        
        Test.startTest();
        LeadProcessor lp = new LeadProcessor();
        id batchJobId = Database.executeBatch(lp,200);
        Test.stopTest();
        
        List<lead> leadsAfterUpdate =[select id, LeadSource from Lead where LeadSource = 'Dreamforce'];
        System.debug(leadsAfterUpdate);
		System.assertEquals(0, leadsAfterUpdate.size());
        }
    }