I am not an Apex developer.  I fumbled my way through creating a trigger in the sanbox to update data on the OpportunityLineItem.  I now need in production and have discovered I need it to go through testing?  Can someone help by providing steps to get this quickly tested and deployed to production?

trigger SetSyndicatedRevenueSchedule on OpportunityLineItem (before insert) {
    List<OpportunityLineItemSchedule> itemschedule = new List<OpportunityLineItemSchedule>();
    for (OpportunityLineItem o: Trigger.new)
    {
      if (o.Product_Subscription__c == False)
      {
        // o.Description = 'Hello World';
        o.ServiceDate = o.Report_Selling_Date__c;
        
        itemschedule.clear();
        // itemschedule = [Select id, ScheduleDate from OpportunityLineItemSchedule where OpportunityLineItemId =: o.Id Order by ScheduleDate ASC];
        itemschedule = [Select ScheduleDate from OpportunityLineItemSchedule where OpportunityLineItemId =: o.Id Order by ScheduleDate ASC];
        System.Debug('Test: ' + itemschedule);
        
        for (OpportunityLineItemSchedule rs: itemschedule)
        {
            rs.ScheduleDate = o.ServiceDate;
            update itemschedule;
        }
      }
    }
}