public void ConcurrencyTests()
        {
            //Get the same record but loaded from two separate contexts so the tracking won't overlap.

            ICustomerRepository repository = new CustomerRepository(_dbContext);
            var secondContext = new EntityContext();

            //add new customer to db.
            var newCustomer = CreateCustomer(repository);

            //load this customer from context 1
            var firstCustomer1 = repository.GetById(newCustomer.CustomerId);
            firstCustomer1.City = "newCity3";

            //load the same customer from context 2
            ICustomerRepository secondRepository = new CustomerRepository(secondContext);
            var firstCustomer2 = secondRepository.GetById(firstCustomer1.CustomerId);

            //Check the states
            Debug.WriteLine(_dbContext.Entry(newCustomer).State);
            Debug.WriteLine(_dbContext.Entry(firstCustomer1).State);
            Debug.WriteLine(secondContext.Entry(firstCustomer2).State);

            //Modify the second customer. We have the same TimeStamp as the original record
            //however the timestamp in the database would've been updated already.
            firstCustomer2.Address = "222 main st" + DateTime.Now.ToString();
            Debug.WriteLine(secondContext.Entry(firstCustomer2).State);

            //This should update that customer.
            repository.Update(firstCustomer1);
            repository.Save();

            //This should throw an exception.
            secondRepository.Update(firstCustomer2);
            secondRepository.Save();

            secondContext.Dispose();
        }
        public void TestNoKey()
        {
            ICustomerRepository repository = new CustomerRepository(_dbContext);
            var bip = new Customer(_validator);
            bip.CustomerId = 10;
            bip.CustomerId = 20;
            var customer = CreateCustomer(repository);
            _dbContext.Customers.Attach(bip);
            bip.CustomerId = 30;
            Debug.WriteLine(_dbContext.Entry(bip).State);
            var newContext = new EntityContext();
            var repository2 = new CustomerRepository(newContext);
            Debug.WriteLine(newContext.Entry(customer).State);
            customer.Address = "555";
            Debug.WriteLine(newContext.Entry(customer).State);
            //newContext.Entry(customer).State = System.Data.EntityState.Modified;
            Debug.WriteLine(newContext.Entry(customer).State);

            newContext.Customers.Attach(customer);
            customer.CustomerId = 0;
            newContext.SaveChanges();

            repository2.Update(customer);
            repository2.Save();
            customer.Address = "556";
            Debug.WriteLine(newContext.Entry(customer).State);
        }