ShoppingCart.Test.cs

public class When_adding_a_cart_item
{
    [SetUp]
    public void Because_Customer_service_and_our_customer_journey_tracker_needs_trace_info()
    {
        _shoppingCart.AddCartItem(cartItem);
    }
    
    [Test]
    public void It_sends_the_correct_message_to_the_event_aggregator
    {
        var messagePlaced = MessageHandler.Messages.FirstOrDefault(message => message.Type == CustomerActiom.CartItemAddedToCart);
        Assert.NotNull(messagePlaced);
        Assert.Equal(messagePlaced.Type, CustomerAction.CartItemAddedToCart);
    }
}