@testSetup static void setupCotacts() {

List<Contact> con = new List<Contact>();
for(Integer i = 0; i < numberOfUserToCreate; i++) {
    con.add(new Contact(
        FirstName= 'abc'+i,
        LastName= 'Smith' + i,
        MailingCity= 'Seattle',
        MailingCountryCode= 'US',
        MailingPostalCode= '23688',
        MailingStreet= '123 street '+ i + 'th ave',
        MiddleName= 'j',
        Personal_Email__c= 'abc' + i +'@gmail.com',
        Preferred_First_Name__c= 'abc'+ i,
        Preferred_Last_Name__c= 'Smith' + i,
        Preferred_Middle_Name__c= 'j',
    ));
}
insert con;
System.debug('Contacts : ' + con.size());