public void AddNewAccountForCustomer_CustomerAlreadyHasAnAccountOfThatType_ShouldFail()
{
//Arrange
Customer customer = new CustomerBuilder().WithId().Build();
AccountType type = Random.NextAccountType();
string accountNumber = Guid.NewGuid().ToString();
var accounts = new List <Account>()
{
new AccountBuilder().WithCustomerId(customer.Id).WithType(type).Build()
};
customer.TrySetAccounts(accounts);
//Act
Result result = _service.AddNewAccountForCustomer(customer, accountNumber, type);
//Assert
Assert.That(result.IsSuccess, Is.False);
Assert.That(result.Message, Contains.Substring("type").IgnoreCase, "The result message should contain the word 'type'.");
_accountRepositoryMock.Verify(repo => repo.Add(It.IsAny <Account>()), Times.Never,
"The 'Add' method of the repository should not have been called.");
}