Test class

TestCreatedDateSetter

@isTest
private class TestCreatedDateSetter{
 
   static testmethod void createAccountTest(){
      Account acc = new Account();
      acc.Name = 'Test';
      insert acc;
      DateTime myDateTime = DateTime.newInstance(1997, 1, 31, 7, 8, 16);
      Test.setCreatedDate(acc.Id, myDateTime );
      Test.startTest();
      system.assertEquals([Select CreatedDate from Account].CreatedDate,myDateTime);
      Test.stopTest();
   }
    
}