AutoFixture partial postprocess composition

Order.cs

public class Order
{
    public decimal TaxPercent { get; set; }
    public decimal DiscountPercent { get; set; }
}

public class ChristmasOrderTax : IPartialPostprocessComposer<Order>
{
    public IPostprocessComposer<Order> Compose(IPostprocessComposer<Order> composer)
    {
        return composer.With(x => x.TaxPercent, (int x) => 200);
    }
}

public class ChristmasOrderDiscount : IPartialPostprocessComposer<Order>
{
    public IPostprocessComposer<Order> Compose(IPostprocessComposer<Order> composer)
    {
        return composer.With(x => x.DiscountPercent, (int x) => 20);
    }
}

OrderTests.cs

[Fact]
public void OrdersHaveChristmasTaxAndDiscount()
{
    // Arrange
    var fixture = new Fixture();
    fixture.Inject(5);
    fixture.Customize<Order>(c => c.Using(new ChristmasOrderTax(), new ChristmasOrderDiscount()));
    
    // Act
    var orders = fixture.CreateMany<Order>();

    // Assert
    orders.Should().OnlyContain(x => x.TaxPercent == 200 && x.DiscountPercent == 20);
}

PartialPostprocessComposer.cs

public interface IPartialPostprocessComposer<T>
{
    IPostprocessComposer<T> Compose(IPostprocessComposer<T> composer);
}

public static class ComposerExtensions
{
    public static IPostprocessComposer<T> Using<T>(this IPostprocessComposer<T> source, IPartialPostprocessComposer<T> composer)
    {
        return composer.Compose(source);
    }

    public static IPostprocessComposer<T> Using<T>(this IPostprocessComposer<T> source, params IPartialPostprocessComposer<T>[] composers)
    {
        return new CompositePartialPostprocessComposer<T>(composers).Compose(source);
    }
}

public class CompositePartialPostprocessComposer<T> : IPartialPostprocessComposer<T>
{
    private readonly IEnumerable<IPartialPostprocessComposer<T>> composers;

    public CompositePartialPostprocessComposer(IEnumerable<IPartialPostprocessComposer<T>> composers)
    {
        this.composers = composers ?? throw new ArgumentNullException(nameof(composers));
    }

    public CompositePartialPostprocessComposer(params IPartialPostprocessComposer<T>[] composers)
        : this(composers.AsEnumerable())
    {
    }

    public IPostprocessComposer<T> Compose(IPostprocessComposer<T> composer)
        => this.composers.Aggregate(composer, (x, c) => x.Using(c));
}