public void GetCostOfAllItems_ShouldReturnTheCostOfAllItems()
{
var productCollection = new ProductCollection
{
Items = new List<Product>
{
new Product {Price = 10},
new Product {Price = 10},
new Product {Price = 10}
}
};
var result = productCollection.GetCostOfAllItems();
Assert.That(result, Is.EqualTo(30));
}