Hi, I've never written a unit test class before and I'm trying to deploy my first trigger.  The trigger itself works fine, the class I wrote to test the trigger works fine, but when I try to deploy Eclipse tells me I have no test coverage on my trigger!  Not true!  Hopefully I'm doing something stupid.

The background details...we have custom fields for Total Costs on our Opportunities and Line Items, so we can calculate margins and markups and such and make sure our salespeople are doing a good job.  The trigger is supposed to do this:
-whenever a line item is created, updated, or deleted
-find the opportunityID of the line item.
-run through every line items attached to that oportunity.
-total all the Total Costs fields on those line items, and shove that total in Total_Costs_Apex__c on the opportunity itself.

The code works fine.  I just can't deploy.

Here's the code:

trigger update_opportunity_costs on OpportunityLineItem (after delete, after insert, after update)
{
    double totalCost = 0.00;
   
    for (OpportunityLineItem oli : Trigger.new)
    {   
         //grab info on every line item attached to the opportunity from the triggering line item.
         for (OpportunityLineItem myOles : [SELECT Total_Costs__c FROM OpportunityLineItem WHERE OpportunityID=:oli.OpportunityId])
         {
          //total the costs of these line items
          totalCost += myOles.Total_Costs__c;
         }
         Opportunity oppty = new Opportunity(Id=oli.OpportunityId);
         //update the opportunity Total Costs Apex field with the total costs of all line items.
         oppty.Total_Costs_Apex__c = totalCost;
         //update the opportunity
         update oppty;  
    }
   
}

~~~~~~
and here's the unit test class I wrote:
public class opportunity_costs_update_test {

    static testMethod void myTest()
    {
   
      Pricebook2 stdPb = [select Id from Pricebook2 where name='Standard' limit 1];   
      PricebookEntry pbe = [select p.Id From PricebookEntry p where p.Name = 'SLA: Silver' and p.Pricebook2Id = :stdPb.Id];

      Opportunity oppty = new Opportunity();
      oppty.name = 'Unit Test Opportunity.';
      oppty.ForecastCategory = 'Pipeline';
      oppty.CloseDate = Date.newInstance(2020,10,10);
      oppty.StageName = 'Proposal/Price Quote';
      oppty.CurrencyIsoCode = 'USD';
      oppty.Pricebook2ID = stdPb.Id;
      insert oppty;
       
      OpportunityLineItem oli = new OpportunityLineItem();
      oli.OpportunityId = oppty.Id;
      oli.Costs_Other__c = 32000.00;
      oli.TotalPrice = 70000.00;
      oli.Quantity = 2;
      oli.PricebookEntryId = pbe.Id;
      insert oli;
    }
}

Any help?  Thanks in advance!