c# - 如何强制 AutoFixture 创建 ImmutableList

Question

在 System.Collections.Generic 中有一个非常有用的 ImmutableList。但是对于这种类型，Autofixture 会抛出异常，因为它没有公共(public)构造函数，它的创建方式类似于 new List<string>().ToImmutableList() .如何告诉 AutoFixture 填充它？

Answer 1

所以感谢@Mark Seemann，我现在可以回答我的问题:

public class ImmutableListSpecimenBuilder : ISpecimenBuilder
{
    public object Create(object request, ISpecimenContext context)
    {
        if (context == null)
        {
            throw new ArgumentNullException(nameof(context));
        }

        var t = request as Type;
        if (t == null)
        {
            return new NoSpecimen();
        }

        var typeArguments = t.GetGenericArguments();
        if (typeArguments.Length != 1 || typeof(ImmutableList<>) != t.GetGenericTypeDefinition())
        {
            return new NoSpecimen();
        }

        dynamic list = context.Resolve(typeof(IList<>).MakeGenericType(typeArguments));

        return ImmutableList.ToImmutableList(list);
    }
}

和用法:

var fixture = new Fixture();
fixture.Customizations.Add(new ImmutableListSpecimenBuilder());
var result = fixture.Create<ImmutableList<int>>();