Does anyone have a test class for this? I have been able to adapt the code to support multiple line enter for a new custom Opportunity Competitors object (junction object between Opportunity and new Competitors object ) but I can't seem to get the necessary coverage and keep getting an error in my test class - System.QueryException: List has no rows for assignment to SObject. I am very new to apex and would appreciate any guidance. Thanks in advance.

Page

<apex:page extensions="OCMultiAdd2Ext" tabStyle="Opportunity" standardController="Opportunity">
    <apex:form >
      <apex:sectionheader title="Opportunity Competitors" subtitle="{!Opportunity.Name}" />
            <apex:pageBlock >
        <p>
          Add one or more Competitors for this Opportunity. You can find competitors by using the Competitor lookup
           or by typing a name in the Competitor field. Only available <a href="https://cs1.salesforce.com/a0S" target="_blank">
           Competitors</a> can be selected. Click Add Row to enter multiple records or Remove Row to delete rows.  
       </p>
       <p>
        Click Save to add all entered Competitors to the Opportunity. Click Cancel to return to the Opportunity 
        record without saving. All data entered will be lost if you click Cancel.
       </p>
        <br />
        <apex:pageMessages />
        
            <apex:pageBlockButtons location="bottom">
                <apex:commandButton value="Save" action="{!save}" />
                <apex:commandButton value="Cancel" action="{!cancel}" />
            </apex:pageBlockButtons>
        
             <apex:pageblocktable value="{!OppComp}" var="OC" Title="Opportunity Competitors" id="table">
                      
         <!-- prevent users changing the Opportunity -->
         <apex:column headervalue="Oppportunity" rendered="false">
            <apex:inputfield value="{!OC.Opportunity__c}" style="width:250px;" />
        </apex:column>
         
         <apex:column headervalue="Competitor" >
           <apex:inputfield value="{!OC.Competitor__c}" style="width:290px;" />
        </apex:column>
    
        <apex:column headervalue="Existing Installation?" >
             <apex:inputfield value="{!OC.Existing_Installation__c}" />
        </apex:column>

        <apex:column headervalue="Notes">
             <apex:inputfield value="{!OC.Notes__c}" style="width:820px;height:30px;" />
        </apex:column>
            </apex:pageBlockTable>
                      
              <div style="text-align:right;margin-right:10px;font-weight:bold;">       
                     <apex:commandLink value="Add Row" action="{!addRow}" rerender="table,error" immediate="true" /> &nbsp;|&nbsp;
                    <apex:commandLink value="Remove Row" action="{!removeRow}" rerender="table,error" immediate="true" />   
        </div>
            
        </apex:pageBlock>
    </apex:form>
</apex:page>

Extension

public class OCMultiAdd2Ext{

    public List<Opportunity_Competitors__c> oppComp {get; set;}
    private final Opportunity opp;
    public OCMultiAdd2Ext(ApexPages.StandardController cstmController) {
        Opp=(Opportunity)cstmController.getrecord();
        oppComp = new List<Opportunity_Competitors__c>();
        Opportunity_Competitors__c OpptyComp = new Opportunity_Competitors__c();
        OpptyComp.Opportunity__c = opp.id;
        oppComp.add(OpptyComp);
        } 
    
    public void addrow(){
        Opportunity_Competitors__c OpptyComp = new Opportunity_Competitors__c();
        OpptyComp.Opportunity__c = opp.id;
        oppComp.add(OpptyComp);}
    
     public void removerow(){
        Integer i = oppComp.size();
        OppComp.remove(i-1);}
    
    public PageReference save(){
        
   //error handling //   
   try{
      insert OppComp;
    }
      catch(Exception e){
           ApexPages.addMessages(e);
       return null;
    }
      
     
    // redirect the user back to the Opportunity record //        
        PageReference opprec = new PageReference('/'+opp.id);
        opprec.setRedirect(true);
        return opprec;
    }
}

Test

@isTest
private class testOCMultiAdd2Ext{
      
       static testMethod void testOpportunityCloseExtOpp() {
          
       //Create an account //
        Account acc = new Account(name='test Account One1');
        acc.Type='Prospect';
        insert acc;
        
         // Create Products 
         Product2 testprod1 = new Product2 (name='test product one1');
         testprod1.productcode = 'test pd code1one';
         insert testprod1;
         
         // Get Pricebook
         Pricebook2 testpb = [select id from Pricebook2 where IsStandard = true];   

        // Add to pricebook
         PricebookEntry testpbe1 = new PricebookEntry ();
         testpbe1.pricebook2id = testpb.id;
         testpbe1.product2id = testprod1.id;
         testpbe1.IsActive = True;
         testpbe1.UnitPrice = 250;
         testpbe1.UseStandardPrice = false;
         insert testpbe1;
 
         //Create an Opp //
        Opportunity Opp = new Opportunity(name='test Oppty One1');
        opp.name='test opp';
        opp.AccountId=acc.Id;
        opp.closeDate=date.today();
        opp.StageName='Qualification';
        opp.Business_Type__c='New Logo';
        opp.Compiler__c='Unknown';
        opp.LOC__c='5M+';
        opp.Platform__c='Linux';
        opp.Purprose_of_Coverity_Evaluation_Pain_Poi__c='Reduce Cost';
        opp.Buying_Budgeting_process__c='Approved';
        opp.LeadSource='Sales';
        opp.Lead_Type__c='Sales Research';
        insert opp;          
 
        // Add to Opp 
        OpportunityLineItem oli1 = new OpportunityLineItem();
        oli1.Quantity = 1000;
        oli1.TotalPrice = 10;
        oli1.PricebookEntryId = testpbe1.id;
        oli1.OpportunityId = opp.id;    
        oli1.Term_M__c = 24;
        oli1.Fulfill_As__c = 'Unlocked';
        insert oli1;
 
        Competitor__c comp = new Competitor__c(Name='Competitor',Website__c='http://www.competitor.com');
        insert comp;
    
        List<Competitor__c> Comptr = [SELECT id from Competitor__c WHERE Id = :comp.id];
        List<Opportunity> oppList = [SELECT id from Opportunity WHERE Id = :opp.id];
    
        Opportunity_Competitors__c oppComp = new Opportunity_Competitors__c(Opportunity__c=opp.Id,Competitor__c=comp.Id,Notes__c='Price is a problem');
        insert oppComp;
        
        Test.startTest();
        PageReference pageRef = Page.OCMultiAdd2;
        Test.setCurrentPageReference(pageRef);
        
        /* Standard controller for the Opportunity */
        ApexPages.StandardController stdCon = new ApexPages.StandardController(opp);
        
        /*Construct the controller extension with the standard controller arg */
        OCMultiAdd2Ext Ext = new OCMultiAdd2Ext(stdCon);
        OpportunityCloseExt con = new OpportunityCloseExt(stdCon);
        PageReference oppPage = con.save();
        System.assert(oppPage != null);                  
        Test.stopTest();
        }
          
          
      
}