AssertObject_pattern.cs

  class ProductAssert
  {
      private readonly Product _product;

      public ProductAssert(Product product)
      {
          _product = product;
      }

      public ProductAssert HaveDiscount(string name, int value)
      {
          _product.Discount.Should().NotBeNull();
          _product.Discount.Name.Should().Be(name);
          _product.Discount.PercentageValue.Should().Be(value);
          _product.BasePrice.Should().NotBe(_product.SalesPrice);
          return this;
      }

      public ProductAssert BeAvailable()
      {
          _product.IsAvailable.Should().BeTrue();
          return this;
      }

      public ProductAssert Cost(decimal price)
      {
          _product.SalesPrice.Should().Be(80);
          return this;
      }
  }