Autofixture - 创建带有余数的浮点型、双精度型或小数型

Question

如何修改 AutoFixture 创建浮点型、双精度型和小数型的方法，以便在创建这些类型时它们也将具有余数？

目前我这样做，但这会引发异常。

var fixture = new Fixture();
fixture.Customize<double>(sb => sb.FromFactory<double>(d => d * 1.33));   //This should add remainder
var value = fixture.Create<double>();

Answer 1

尝试使用相同类型的值 (

double

) 重新定义类型 (

double

) 实际上会产生无限递归。但是，您可以通过将种子输入更改为另一种类型（例如一个

int

：

var fixture = new Fixture();
fixture.Customize<double>(c => c.FromFactory<int>(i => i * 1.33));
var value = fixture.Create<double>();

双精度现在也往往有小数值。

Answer 2

一种选择是使用自定义

ISpecimenBuilder

:

var fixture = new Fixture();
fixture.Customizations.Add(
    new RandomDoublePrecisionFloatingPointSequenceGenerator());

RandomDoublePrecisionFloatingPointSequenceGenerator

可能如下所示：

internal class RandomDoublePrecisionFloatingPointSequenceGenerator
    : ISpecimenBuilder
{
    private readonly object syncRoot;
    private readonly Random random;

    internal RandomDoublePrecisionFloatingPointSequenceGenerator()
    {
        this.syncRoot = new object();
        this.random = new Random();
    }

    public object Create(object request, ISpecimenContext context)
    {
        var type = request as Type;
        if (type == null)
            return new NoSpecimen(request);

        return this.CreateRandom(type);
    }

    private double GetNextRandom()
    {
        lock (this.syncRoot)
        {
            return this.random.NextDouble();
        }
    }

    private object CreateRandom(Type request)
    {
        switch (Type.GetTypeCode(request))
        {
            case TypeCode.Decimal:
                return (decimal)
                    this.GetNextRandom();

            case TypeCode.Double:
                return (double)
                    this.GetNextRandom();

            case TypeCode.Single:
                return (float)
                    this.GetNextRandom();

            default:
                return new NoSpecimen(request);
        }
    }
}

Answer 3

似乎没有办法拦截/修改创建的值，但我认为我更喜欢的解决方案是使用第二个

Fixture

。

public static IFixture FixDecimals(
   this IFixture me
) {
   var f = new Fixture();
   var r = new Random();
   me.Register<float>(() => f.Create<float>() + r.NextSingle());
   me.Register<double>(() => f.Create<double>() + r.NextDouble());
   me.Register<decimal>(() => f.Create<decimal>() + (decimal)r.NextDouble());
   return me;
}