The 'AccountTrigger' trigger isn't working correctly. Make sure that the trigger inserts Account records with matching BillingState and ShippingState values

public class AccountTriggerHandler {
    public static void CreateAccounts(List<Account> accList) {
        for(Account acc : accList) {
            if(acc.ShippingState != acc.BillingState) {
                acc.ShippingState = acc.BillingState;
            }
        }
    }
}

Account Trigger

trigger AccountTrigger on Account (before insert) {
    if(Trigger.isBefore && Trigger.isInsert) {
        AccountTriggerHandler.CreateAccounts(Trigger.New);
    }
}

AccountTriggerTest

@isTest
public class AccountTriggerTest {
    @isTest static void createAccounts() {
        List<Account> accList = new List<Account>();
        for(Integer i=0;i<200;i++) {
            Account acc = new Account();
            acc.Name = 'Test Account '+i;
            acc.First_Name__c = 'Acc FName '+i;
            acc.Last_Name__c = 'Acc LName '+i;
            acc.BillingState = 'CA';
            accList.add(acc);
        }
        Test.startTest();
        insert accList;
        Test.stopTest();
        List<Account> verifyAccList = [SELECT Id, ShippingState FROM Account];
        for(Account acc : verifyAccList) {
            System.assertEquals('CA', acc.ShippingState);
        }
    }
}

Hi All, I'm getting the following error - The 'AccountTrigger' trigger isn't working correctly. Make sure that the trigger inserts Account records with matching BillingState and ShippingState values, What could be the reason for this issue?