Please suggest me if any one knows the below code pass in test class.

for (Accounts__c acc : (List<Accounts__c>)Trigger.New)
        {
            if((String.isNotBlank(acc.Billing_Country__c) && trigger.isInsert) || ((String.isNotBlank(acc.Billing_Country__c) && trigger.isUpdate && ((Map<Id, Accounts__c>)Trigger.oldMap).get(acc.Id).Billing_Country__c != acc.Billing_Country__c)))
            {
                UpdatedAccs.add(acc);
                setCountries.add(acc.Billing_Country__c);
            }    
                
        }