public void CustomerTests()
{
Customer newCustomer = new Customer();
newCustomer.FirstName = "Sam";
newCustomer.LastName = "Spade";
newCustomer.Type = Customer.CustomerType.Current;
repo.AddCustomerToDirectory(newCustomer);
Console.WriteLine($"This customer's full name is {newCustomer.FullName}." +
$"Customer's type is {newCustomer.Type}.");
}