public void Apply_WithLessThanMinimumProductForPromotionToBeAvailed_NoPromotionApplied()
    {
        IList <IProduct> products = SetupProduct("ProductB", 30, 1);

        var promotion           = new Promotion.PromotionB();
        var totalValueOfProduct = promotion.Apply(products);

        Assert.Equal(30, totalValueOfProduct);
    }
    public void Apply_WithMoreThanMinimumProductForPromotionToBeAvailed_PromotionAppliedForRelevantProducts()
    {
        IList <IProduct> products = SetupProduct("ProductB", 30, 3);

        var promotion           = new Promotion.PromotionB();
        var totalValueOfProduct = promotion.Apply(products);

        Assert.Equal(75, totalValueOfProduct);
    }