Salesforce trailhead - Asynchronous Apex Using Batch Apex: The code creates a batch class to update lead object

LeadProcessor.cls

global class LeadProcessor implements Database.Batchable<sObject> {
    global Integer count = 0;
    
    global Database.QueryLocator start (Database.BatchableContext bc) {
        return Database.getQueryLocator('Select Id, LeadSource from lead');
    }
    
    global void execute (Database.BatchableContext bc,List<Lead> l_lst) {
        List<lead> l_lst_new = new List<lead>();
        for(lead l : l_lst) {
            l.leadsource = 'Dreamforce';
            l_lst_new.add(l);
            count+=1;
        }
        update l_lst_new;
    }
	
    global void finish (Database.BatchableContext bc) {
        system.debug('count = '+count);
    }
}

LeadProcessorTest.cls

@isTest
public class LeadProcessorTest {
    
    @isTest    
    public static void testit() {
        List<lead> l_lst = new List<lead>();
        for (Integer i = 0; i<200; i++) {
            Lead l = new lead();
            l.LastName = 'name'+i;
            l.company = 'company';
            l.Status =  'somestatus';
            l_lst.add(l);
        }
        insert l_lst;
        
        test.startTest();
        
        Leadprocessor lp = new Leadprocessor();
        Id batchId = Database.executeBatch(lp);
        Test.stopTest();
            
    }

}

how to get 100% code coverage?
can we write test case for execute method?