I have a trigger as follows:

trigger LeadConvert on Lead (after update) {

  // no bulk processing; will only run from the UI
  if (Trigger.new.size() == 1) {

    if (Trigger.old[0].isConverted == false && Trigger.new[0].isConverted == true) {

      // if a new account was created
      if (Trigger.new[0].ConvertedAccountId != null) {

        // update the converted account with some text from the lead
        Account a = [Select a.Id, a.Initial_Payment__c, a.BPS__c,a.Monthly_Payment__c, a.X401_k_Plan_Type__c From Account a Where a.Id = :Trigger.new[0].ConvertedAccountId];
        if (a.X401_k_Plan_Type__c == 'Individual')
        {
            a.NumberOfEmployees = Integer.Valueof(Trigger.new[0].Number_of_Owners__c);
        }
        update a;

      }         

      }        

    }

  
}

It maps converted lead field to an account field.

Have written a test for the same which is giving 0% code coverage.

@isTest
private class LeadConvertTest {
@testSetup static void setup() {
        User users2=createUser();
        system.runAs(users2){
            Lead l1=new Lead();
            l1.LastName='test';
            l1.Number_of_Owners__c = 25;
            insert l1;
   
        }
    }
    
    @isTest
    static void updateAccount1(){
        user us2=[select Id from user where  Email ='xxx@ddd.com'];
        system.runAs(us2){
            Account a2=[select Id from Account limit 1];
            a2.X401_k_Plan_Type__c = 'Individual';
            update a2;
            
        }
        
    }
    
    
    private static user createUser(){
        User plannerUser2 = new User(
            ProfileId = [SELECT Id,name FROM Profile where name='System Administrator'].Id,
            LastName = 'last',
            Email = 'xxx@ddd.com',
            Username = 'xxx@ddd.com' + System.currentTimeMillis(),
            CompanyName = 'TEST1',
            Title = 'title',
            Alias = 'alias',
            TimeZoneSidKey = 'America/Los_Angeles',
            EmailEncodingKey = 'UTF-8',
            LanguageLocaleKey = 'en_US',
            LocaleSidKey = 'en_GB',
            IsActive=true);
        database.insert(plannerUser2);
        return plannerUser2;
    }
    
}

I am new to development and any help woulf be graetly appreciated.