I have searched on here for a case that is similar to my own, but I can't find anything that matches why I'm getting the SQL error in my test. I'm very new to Apex and have been editing/duplicating code from a previous developer.

Error =

FATAL_ERROR System.QueryException: List has no rows for assignment to SObject

Does anyone know why this would be failing? The trigger works in the sandbox but it will not let me deploy to production as the test fails.

Here is my class test:

@isTest
public class OppReSEMTest {
        public static testMethod void Tester() {

    OpportunityLineItem oli = [select Id,OpportunityId from OpportunityLineItem
                                        where PricebookEntry.Product2.Production_Item__c=true
                                        limit 1];

    Opportunity o = [select Id,StageName,Finance_VAT_Exempt__c,Sector__c,

                                        PO_Number__c,Finance_Email__c from Opportunity
                                               where Id=:oli.OpportunityId
                                               limit 1];   

    o.StageName='Closed Lost';
    o.Finance_VAT_Exempt__c='Yes';
    update o;
    o.StageName='Closed Won';
    o.Finance_VAT_Exempt__c='Yes';
    o.PO_Number__c='0987654';
    o.Finance_Email__c='[email protected]';
    o.Sector__c='Charity';
    update o;
    }

}

Here is my trigger:

trigger OppReSEM on Opportunity (after insert, after update) {
    try {
        if (Test.isRunningTest() || ! OnceSEM.hasAlreadyRound()) {
            set<id> oids = new set<id>();

            for (Opportunity o:trigger.new) {
                    if (trigger.newMap.get(o.id).Create_New_Production_Orders__c == TRUE)
                {
                    oids.add(o.id);
        }
            }
            system.debug('!!!!!!!!!!!!!!!!oids size!!!!!!' + oids.size());

            if (oids.size() > 0) {
                list<OpportunityLineItem> loli = ([
                    select Id,
                    Opportunity.Id,
                    Opportunity.Name,
                    Quantity,
                    Account__c,
                    PricebookEntry.Product2.Id,
                    PricebookEntry.Product2.Name
                    from
                    OpportunityLineItem
                    where Opportunity.Id IN: oids
                    and
                    PricebookEntry.Product2.Quantity_Override__c=true
                    and
                    OpportunityLineItem.Production_Order_Created__c=false
                ]);

                system.debug('!!!!!!!!!!!!!!!!loli size!!!!!!' + loli.size());


                if (loli.size() > 0) {
                    OnceFO.setAlreadyRound();

                    list<Sales_Order__c> li = new list<Sales_Order__c>();

                    for (OpportunityLineItem oli : loli) {
                        string semn = (oli.PricebookEntry.Product2.Name + ' | ' + oli.Opportunity.Name + ' | ' + oli.Account__c);

   //Get sizes of Goal and Strategy in the event they are longer than 80 char and need to be truncated
   Integer size1 = semn.length();


   //If Goal or Strategy are longer than 80 characters they need to be truncated
   if(size1> 80){
         semn= semn.substring(0, 79);
   }
                        Sales_Order__c so = new Sales_Order__c(
                            Name=semn,
                            Opportunity__c=oli.Opportunity.Id,
                            Product__c=oli.PricebookEntry.Product2.Id
                        );
                        li.add(so);
                        if (li.size() > 198) {
                            insert li;
                            li.clear();
                        }
                    }
                    if (li.size() > 0) {
                        insert li;
                        li.clear();
                    }
                }
            }
        }
    } catch (Exception exall) {}
}

Here is my class:

public class OnceSEM {
      private static boolean alreadyRound = false;
    public static boolean hasAlreadyRound() {
        return alreadyRound;
    }
   public static void setAlreadyRound() {
        alreadyRound = true;
    }


}