Class:
global class ContractRenewalBatchJob implements Database.Batchable<sObject>
{
    global Database.QueryLocator start(Database.BatchableContext BC)
    {
        Date endDateContract = system.today() + Integer.valueOf(Label.KHCPQ_RenewalEmailDuration);
        Date endDateContract1 = system.today() + Integer.valueOf(Label.KHCPQ_RenewalEmailDuration1);
        Date endDateContract2 = system.today() + Integer.valueOf(Label.KHCPQ_RenewalEmailDuration2);
        Date endDateContract3 = system.today() + Integer.valueOf(Label.KHCPQ_RenewalEmailDuration3);
        
        String query = 'select id,Account.Name,Owner.Email,Owner.Name,Ownerid,EndDate,ContractNumber,CustomerSigned.id from Contract where (enddate=:endDateContract OR enddate=:endDateContract1 OR enddate=:endDateContract2 OR enddate=:endDateContract3) and (SBQQ__RenewalForecast__c=false and SBQQ__RenewalQuoted__c=false)';
        List<sObject> sobjList = Database.query(query);
        system.debug('ttt'+sobjList);
        return Database.getQueryLocator(query);
    }
    global void execute(Database.BatchableContext BC, List<Contract> scope)
    {
        try
        {
            List<Messaging.SingleEmailMessage>  myEmails = new List<Messaging.SingleEmailMessage>();
            for(Contract c:scope)
            {
                system.debug('Contract : ' + c);
                String body;
                body = 'Hi ' + c.Owner.Name + ',<br/><br/>';
                body = body + 'Contract ' + c.ContractNumber + ' is expiring on ' + c.EndDate.month() + '/' + c.EndDate.day() + '/' + c.EndDate.year() + '.<br/>';
                body = body + '<br/>Please renew the Contract ASAP. You can access the contract in the URL below:<br/><br/>';
                body = body + Label.WebsiteURL + '/' + c.id + '<br/><br/>';
                body = body + 'Regards,<br/>AFH Sales Ops Team';
                
                Messaging.SingleEmailMessage mail = new Messaging.SingleEmailMessage();
                mail.setHTMLBody(body);
                mail.setToAddresses(new String[]{c.owner.email});
                mail.setSubject('ACTION REQUIRED: Your \"' + c.Account.Name + '\" Contract Requires Renewal');
                myEmails.add(mail);
            }
            if(myEmails.size() > 0)
            {
                Messaging.sendEmail(myEmails,false);
            }
        }
        catch(Exception ex)
        {
            system.debug('Exception : ' + ex.getMessage());
        }
    }
    global void finish(Database.BatchableContext BC)
    {
    }
}
test class:
@isTest
public class ContractRenewalBatchJobTest 
{
    static testMethod void testMethod1()
    {
        User us = [Select id from User where Id = :UserInfo.getUserId()];
        Date startDateWithinRange =  system.today();   
        Date endDateWithinRange = system.today() + 29;
        Date endDateWithinRange1 = system.today() + 59;
        Date endDateWithinRange2 = system.today() + 89;
        Date endDateWithinRange3 = system.today() + 119;
        Account acc1 = KHCPQ_Test_DataFactory.createAccount('Parent Account','Active','Street 1','123');
        Contract contract1 = KHCPQ_Test_DataFactory.createContract(acc1.Id,'Draft',startDateWithinRange,endDateWithinRange);
        Contract contract2 = KHCPQ_Test_DataFactory.createContract(acc1.Id,'Draft',startDateWithinRange,endDateWithinRange1);
        Contract contract3 = KHCPQ_Test_DataFactory.createContract(acc1.Id,'Draft',startDateWithinRange,endDateWithinRange2);
        Contract contract4 = KHCPQ_Test_DataFactory.createContract(acc1.Id,'Draft',startDateWithinRange,endDateWithinRange3);
        System.runAs(us)
        Test.startTest();
        ContractRenewalBatchJob obj = new ContractRenewalBatchJob();
        DataBase.executeBatch(obj);
        ContractRenewSchedule sch = new ContractRenewSchedule();
        String cronStr = '0 0 0,12 * * ?';
        system.schedule('testJob', cronStr, sch);
        Test.stopTest();
    }
}