hello community, when I was executing with a debug to check on my class this occured:



that's the code for the class:

public class HelperContactTrigger {
    //static method
    public static List<Account> sendEmail(List<Account> accounts) {

        //query on template object
        EmailTemplate et=[Select id from EmailTemplate where name= 'Sales: New Customer Email' limit 1];

        system.debug(et);   //debug to check the template

        //list of emails
        List<Messaging.SingleEmailMessage> emails = new List<Messaging.SingleEmailMessage>();

        //loop
        for(Account con : accounts){

            //check for Account
            if(con.PersonEmail == null && con.PersonEmail != null){

                //initiallize messaging method
                Messaging.SingleEmailMessage singleMail = new Messaging.SingleEmailMessage();

                //set object Id
                singleMail.setTargetObjectId(con.Id);

                //set template Id
                singleMail.setTemplateId(et.Id);

                //flag to false to stop inserting activity history
                singleMail.setSaveAsActivity(false);

                //add mail
                emails.add(singleMail);
            }
        }

        //send mail
        Messaging.sendEmail(emails);
        return accounts;
    }
}

What do I do? I checked the code and everything a million times.
I was having difficulties running a test class for this programm (System.QueryException: List has no rows for assignment to SObject)
so I have to check if the query statement really does what it's supposed to, it has to work as a mailtrigger when a new account is added but the query is having issues so I have to know what the real problem is.

This is the test class:

@isTest
private class HelperContactTriggerTestneuer {
public static testMethod void myTestMethod() {

        Account acc = new Account(Name = 'Test Test');
        insert acc;

        List<Account> sendMail = [select id from account where (Name='Test Test') and id=:acc.id];
   EmailTemplate testTemplate=new EmailTemplate(Name='Neuer Kunde',DeveloperName='Neuer_Kunde',FolderId=Userinfo.getUserId());
   insert testTemplate;

        HelperContactTrigger.sendEmail(sendMail);
        System.assert(acc !=null);
        
        }
        }


thanks in advance :)