public void ShouldThrowExceptionWhenDecrementIsCalledAndThereAreNoItems()
{
_customer = _testHelper.GetDefaultCustomer(0);
Assert.Throws(typeof(ApplicationException), () => _customer.DecrementItems());
}
public void NumberShouldDecreaseByOneWhenDecrementIsCalled()
{
_customer = _testHelper.GetDefaultCustomer(5);
_customer.DecrementItems();
Assert.AreEqual(4, _customer.NumberOfItems);
}