global class or_guestsSchedulable implements Schedulable{

    global void execute(SchedulableContext sc)
    {
   or_service.getGuests();
    }
}

private class or_guestsSchedulableTest {

    private static testMethod void or_guestsSchedulable() {

    Test.startTest();
        Datetime dt = Datetime.now().addMinutes(1);
        String CRON_EXP = '0 '+ dt.minute() + ' * ' + dt.day() + ' ' + dt.month() + ' ? ' + dt.year();
        or_guestsSchedulableTest.execute('Sample_Heading', CRON_EXP, new  or_guestsSchedulable () );
        Test.stopTest();
    }
    }

private class or_guestsSchedulableTest {

private static testMethod void or_guestsSchedulableMethodTest() {

Test.startTest();
      String jobId = System.schedule('Sample_Heading', CRON_EXP, new or_guestsSchedulable());
    Test.stopTest();
}
}

// Schedule the test job
        String jobId = System.schedule('Sample_Heading',
            CRON_EXP,
            new or_guestsSchedulable());

or_guestsSchedulableTest.execute('Sample_Heading', CRON_EXP, new  or_guestsSchedulable () );