How to write a test class for this page reference method.i am unable to cover this part on my controllerclass.

public pagereference saveRecord()
     {
        List<Min_Tier_threshold__c> discLocal=accon.clone() ;
        List<Min_Tier_threshold__c> discLocal2=new List<Min_Tier_threshold__c>(accon);
         integer i=0;
        for(Min_Tier_threshold__c Tier:accon){
        
               if(Tier.SMS_Threshold__c==null && Tier.SMS_Tier__c ==null && Tier.SMS_Tier_Description__c==null )
               { discLocal2.remove(i); }
               
               else if(Tier.SMS_Threshold__c==null || Tier.SMS_Tier__c ==null || Tier.SMS_Tier_Description__c==null )
               {
               ApexPages.Message msg = new ApexPages.Message(ApexPages.Severity.ERROR,'You must enter all required fields');
               ApexPages.addMessage(msg);
               return null;
              }
              i++;
           }
          upsert discLocal2; 
        PageReference pageRef = new PageReference('/apex/ExhibitAadminTier?retURL=/apex/ExhibitAAdmin');
        pageref.setRedirect(true);
        return pageref; 
      }
    
     public PageReference cancel()  
     {
      PageReference pg1=new PageReference('/apex/ExhibitAadminTier?retURL=/apex/ExhibitAAdmin');
      pg1.setRedirect(true);
      return pg1;
     }  
   public void addrow() {
            
        Min_Tier_threshold__c proTier = new Min_Tier_threshold__c();
        proTier .SMS_Threshold__c= (agnt.SMS_Threshold__c);
        proTier .SMS_Tier__c =(agnt.SMS_Tier__c );
        proTier .SMS_Tier_Description__c=(agnt.SMS_Tier_Description__c);
        
        accon.add(proTier );
       }  


this is my test class---
PageReference pageRef = Page.ExhibitAadminTier; // Adding VF page Name here
        pageRef.getParameters().put('id', String.valueOf(min1.id));//for page reference
        Test.setCurrentPage(pageRef);
        
        ApexPages.currentPage().getParameters().put('RecordType','ExhibitAadminTier');
        ApexPages.StandardController sc = new ApexPages.standardController(min1);
        ExhibitAadminTier controller = new ExhibitAadminTier(sc);
  
        controller.saveRecord();
        controller.addrow();
        controller.cancel();